Handoff for satellite communication

ABSTRACT

Various aspects of the disclosure relate to handoff (e.g., idle mode handoff or other types of handoff) for a user terminal. In some aspects, a user terminal (UT) may request idle mode handoff information from a ground network (GN). Idle mode handoff information may include, for example, start times for a set of satellites, whereby each particular start time indicates when the UT may handoff to the corresponding satellite. The UT may send the request for idle mode handoff information to the GN when the UT has a defined number of valid entries (e.g., one unexpired entry) remaining in an idle mode handoff table. In some aspects, the idle UT may send the request for idle mode handoff information to the GN based on a time associated with a particular entry in an idle mode handoff table or based on a time of validity of an idle mode handoff table.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation-in-part of patent application Ser.No. 15/141,641 filed in the U.S. Patent and Trademark Office on Apr. 28,2016, which is a continuation-in-part of patent application Ser. No.14/856,933 filed in the U.S. Patent and Trademark Office on Sep. 17,2015, and claims priority to and the benefit of provisional patentapplication No. 62/156,063 filed in the U.S. Patent and Trademark Officeon May 1, 2015, and provisional patent application No. 62/409,289 filedin the U.S. Patent and Trademark Office on Oct. 17, 2016, the entirecontent of each of which is incorporated herein by reference.

INTRODUCTION

Various aspects described herein relate to satellite communication, andmore particularly but not exclusively, to handoff for non-geosynchronoussatellite communication.

Satellite-based communication systems may include gateways and one ormore satellites to relay communication signals between the gateways andone or more user terminals. A gateway is an earth station having anantenna for transmitting signals to, and receiving signals from,communication satellites. A gateway provides communication links, usingsatellites, for connecting a user terminal to other user terminals orusers of other communication systems, such as a public switchedtelephone network, the Internet and various public and/or privatenetworks. A satellite is an orbiting receiver and repeater used to relayinformation.

A satellite can receive signals from and transmit signals to a userterminal provided the user terminal is within the “footprint” of thesatellite. The footprint of a satellite is the geographic region on thesurface of the Earth within the range of signals of the satellite. Thefootprint is usually geographically divided into “beams,” through theuse of antennas (e.g., the antennas may be used to create fixed, staticbeams or may be used to create dynamically adjustable beams throughbeam-forming techniques). Each beam covers a particular geographicregion within the footprint. Beams may be directed so that more than onebeam from the same satellite covers the same specific geographic region.In addition, beams from multiple satellites may be directed to cover thesame geographic region. A cell may constitute any forward link frequencyand/or return link frequency within a beam. In a case where each beamuses only one frequency, the terms “cell” and “beam” may beinterchangeable.

Geosynchronous satellites have long been used for communication. Ageosynchronous satellite is stationary relative to a given location onthe Earth, and thus there is little timing shift and Doppler frequencyshift in radio signal propagation between a communication transceiver onthe Earth and the geosynchronous satellite. However, becausegeosynchronous satellites are limited to a geosynchronous orbit (GSO),which is a circle having a radius of approximately 42,164 km from thecenter of the Earth directly above the Earth's equator, the number ofsatellites that may be placed in the GSO is limited.

As alternatives to geosynchronous satellites, communication systemswhich utilize a constellation of satellites in non-geosynchronousorbits, such as low-earth orbits (LEO), have been devised to providecommunication coverage to the entire Earth or at least large parts ofthe Earth. In non-geosynchronous satellite-based systems, such as LEOsatellite-based systems, the satellites move relative to ground-basedcommunication devices such as gateways or user terminals. Thus, at somepoint in time, a user terminal will be handed-off from one satellite toanother. Consequently, there is a need for techniques that enable a userterminal to be efficiently handed-off to the best available satellite.

SUMMARY

The following presents a simplified summary of some aspects of thedisclosure to provide a basic understanding of such aspects. Thissummary is not an extensive overview of all contemplated features of thedisclosure, and is intended neither to identify key or critical elementsof all aspects of the disclosure nor to delineate the scope of any orall aspects of the disclosure. Its sole purpose is to present variousconcepts of some aspects of the disclosure in a simplified form as aprelude to the more detailed description that is presented later.

In one aspect, the disclosure provides a method for communicationincluding: identifying a time associated with a particular entry of aset of handoff entries, wherein the set of handoff entries identifies aset of satellites for handoff of the apparatus; determining, based onthe identified time, whether to send a request for an updated set ofhandoff entries; and sending the request for an updated set of handoffentries if the determination is to send the request.

In some aspects, the set of handoff entries may include (e.g., may be)an idle mode handoff table. In some aspects, the time may include astart time for a handoff to one satellite of the set of satellites. Insome aspects, the particular entry may include a last entry of the setof handoff entries. In some aspects, the set of satellites may be for anidle mode operation of the apparatus. In some aspects, the time mayindicate when the apparatus is to handoff to one satellite of the set ofsatellites while the apparatus is in an idle mode. In some aspects, theset of handoff entries may identify times at which the apparatus when inidle mode is to handoff to each satellite of the set of satellites. Insome aspects, the set of handoff entries may include, for eachsatellite, a time for the apparatus when in idle mode to handoff to thesatellite. In some aspects, the request may be communicated when theapparatus establishes a Radio connection with a ground network. In someaspects, the apparatus may include (e.g., may be) a user terminal. Insome aspects, the request may be sent to a ground network.

In one aspect, the disclosure provides an apparatus configured forcommunication that includes a memory and a processor coupled to thememory. The processor and the memory are configured to: identify a timeassociated with a particular entry of a set of handoff entries, whereinthe set of handoff entries identifies a set of satellites for handoff ofthe apparatus; determine, based on the identified time, whether to senda request for an updated set of handoff entries; and send the requestfor an updated set of handoff entries if the determination is to sendthe request.

In some aspects, the set of handoff entries may include an idle modehandoff table; and the idle mode handoff table may include, for eachsatellite, a time for the apparatus when in idle mode to handoff to thesatellite. In some aspects, the processor and the memory may be furtherconfigured to send an indication of the time in conjunction with thesending of the request. In some aspects, the processor and the memorymay be further configured to send an indication of a time of validityassociated with the set of handoff entries in conjunction with thesending of the request. In some aspects, the processor and the memorymay be further configured to: receive the updated set of handoff entriesafter sending the request; and hand off to a satellite identified by theupdated set of handoff entries at a time indicated by the updated set ofhandoff entries. In some aspects, the processor and the memory may befurther configured to receive an indication of at least one carrierfrequency at which a next cell that provides coverage for the apparatuswill be transmitting; and the handoff to the satellite identified by theupdated set of handoff entries may be conducted on the at least onecarrier frequency. In some aspects, the processor and the memory may befurther configured to: determine location information for the apparatus;and send the location information in conjunction with the sending of therequest.

In one aspect, the disclosure provides an apparatus configured forcommunication. The apparatus including: means for identifying a timeassociated with a particular entry of a set of handoff entries, whereinthe set of handoff entries identifies a set of satellites for handoff ofthe apparatus; means for determining, based on the identified time,whether to send a request for an updated set of handoff entries; andmeans for sending the request for an updated set of handoff entries ifthe determination is to send the request.

In some aspects, the means for sending may be configured to send anindication of the time in conjunction with the sending of the request.In some aspects, the means for sending may be configured to send anindication of a time of validity associated with the set of handoffentries in conjunction with the sending of the request. In some aspects,the apparatus may include: means for receiving the updated set ofhandoff entries after sending the request; and means for handing off theapparatus to a satellite identified by the updated set of handoffentries at a time indicated by the updated set of handoff entries. Insome aspects, the means for receiving may be configured to receive anindication of at least one carrier frequency at which a next cell thatprovides coverage for the apparatus will be transmitting; and thehandoff to the satellite identified by the updated set of handoffentries may be conducted on the at least one carrier frequency. In someaspects, the apparatus may include means for determining locationinformation for the apparatus, wherein the means for sending may befurther configured to send the location information in conjunction withthe sending of the request.

In one aspect, the disclosure provides a non-transitorycomputer-readable medium storing computer-executable code, includingcode to: identify a time associated with a particular entry of a set ofhandoff entries, wherein the set of handoff entries identifies a set ofsatellites for handoff of the apparatus; determine, based on theidentified time, whether to send a request for an updated set of handoffentries; and send the request for an updated set of handoff entries ifthe determination is to send the request.

In one aspect, the disclosure provides a method for communicationincluding: identifying a quantity of valid entries in a set of handoffentries, wherein the set of handoff entries identifies a set ofsatellites for handoff of the apparatus; determining, based on theidentified quantity, whether to send a request for an updated set ofhandoff entries; and sending the request for an updated set of handoffentries if the determination is to send the request.

In some aspects, the determination of whether to send the request for anupdated set of handoff entries may include determining whether the setof handoff entries includes only one valid entry. In some aspects, therequest may be communicated when the apparatus establishes a Radioconnection with a ground network. In some aspects, the set of handoffentries may identify times at which the apparatus when in idle mode isto handoff to each satellite of the set of satellites.

In one aspect, the disclosure provides an apparatus configured forcommunication that includes a memory and a processor coupled to thememory. The processor and the memory are configured to: identify aquantity of valid entries in a set of handoff entries, wherein the setof handoff entries identifies a set of satellites for handoff of theapparatus; determine, based on the identified quantity, whether to senda request for an updated set of handoff entries; and send the requestfor an updated set of handoff entries if the determination is to sendthe request.

In some aspects, the processor and the memory may be further configuredto: receive the updated set of handoff entries after sending therequest; and hand off to a satellite identified by the updated set ofhandoff entries at a time indicated by the updated set of handoffentries. In some aspects, the processor and the memory may be furtherconfigured to receive an indication of at least one carrier frequency atwhich a next cell that provides coverage for the apparatus will betransmitting; and the handoff to the satellite identified by the updatedset of handoff entries may be conducted on the at least one carrierfrequency. In some aspects, the processor and the memory may be furtherconfigured to: determine location information for the apparatus; andsend the location information in conjunction with the sending of therequest.

In one aspect, the disclosure provides an apparatus configured forcommunication. The apparatus including: means for identifying a quantityof valid entries in a set of handoff entries, wherein the set of handoffentries identifies a set of satellites for handoff of the apparatus;means for determining, based on the identified quantity, whether to senda request for an updated set of handoff entries; and means for sendingthe request for an updated set of handoff entries if the determinationis to send the request.

In some aspects, the apparatus may include: means for receiving theupdated set of handoff entries after sending the request; and means forhanding off the apparatus to a satellite identified by the updated setof handoff entries at a time indicated by the updated set of handoffentries. In some aspects, the means for receiving may be configured toreceive an indication of at least one carrier frequency at which a nextcell that provides coverage for the apparatus will be transmitting; andthe handoff to the satellite identified by the updated set of handoffentries may be conducted on the at least one carrier frequency. In someaspects, the apparatus may include means for determining locationinformation for the apparatus, wherein the means for sending may beconfigured to send the location information in conjunction with thesending of the request.

In one aspect, the disclosure provides a non-transitorycomputer-readable medium storing computer-executable code, includingcode to: identify a quantity of valid entries in a set of handoffentries, wherein the set of handoff entries identifies a set ofsatellites for handoff of the apparatus; determine, based on theidentified quantity, whether to send a request for an updated set ofhandoff entries; and send the request for an updated set of handoffentries if the determination is to send the request.

In one aspect, the disclosure provides a method for communicationincluding: identifying a time of validity associated with a set ofhandoff entries, wherein the set of handoff entries identifies a set ofsatellites for handoff of another apparatus; determining, based on theidentified time of validity, whether to send an updated set of handoffentries; and sending the updated set of handoff entries if thedetermination is to send the updated set of handoff entries.

In some aspects, the time of validity indicates a duration of time thatthe set of handoff entries may be valid. In some aspects, theidentification of the time of validity may include receiving anindication of the time of validity. In some aspects, the identificationof the time of validity may include: receiving an indication of a timeassociated with a particular entry of the set of handoff entries; anddetermining the time of validity based on the received indication. Insome aspects, the identification of the time of validity may includedetermining a time associated with a last valid entry in the set ofhandoff entries. In some aspects, the set of handoff entries may includea last set of handoff entries sent by the apparatus to the otherapparatus. In some aspects, the apparatus may include (e.g., may be) aground network. In some aspects, the updated set of handoff entries maybe sent to a user terminal.

In one aspect, the disclosure provides an apparatus configured forcommunication that includes a memory and a processor coupled to thememory. The processor and the memory are configured to: identify a timeof validity associated with a set of handoff entries, wherein the set ofhandoff entries identifies a set of satellites for handoff of anotherapparatus; determine, based on the identified time of validity, whetherto send an updated set of handoff entries; and send the updated set ofhandoff entries if the determination is to send the updated set ofhandoff entries.

In some aspects, the processor and the memory may be further configuredto receive location information for the other apparatus. In someaspects, the processor and the memory may be further configured togenerate the updated set of handoff entries based on the locationinformation; and the updated set of handoff entries may be sent to theother apparatus. In some aspects, the processor and the memory may befurther configured to receive location information for the otherapparatus; and the determination of whether to send the updated set ofhandoff entries may be further based on the location information. Insome aspects, the processor and the memory may be further configured toreceive location information for the other apparatus. In some aspects,the processor and the memory may be further configured to determinemovement of the other apparatus based on the location information; andthe determination of whether to send the updated set of handoff entriesmay be further based on the movement of the other apparatus. In someaspects, the processor and the memory may be further configured to:receive location information for the other apparatus; determine movementof the other apparatus based on the location information; and determinehow many updated handoff entries to send based on the movement of theother apparatus.

In one aspect, the disclosure provides an apparatus configured forcommunication. The apparatus including: means for identifying a time ofvalidity associated with a set of handoff entries, wherein the set ofhandoff entries identifies a set of satellites for handoff of anotherapparatus; means for determining, based on the identified time ofvalidity, whether to send an updated set of handoff entries; and meansfor sending the updated set of handoff entries if the determination isto send the updated set of handoff entries.

In some aspects, the apparatus may include: means for receiving locationinformation for the other apparatus; and means for generating theupdated set of handoff entries based on the location information,wherein the updated set of handoff entries may be sent to the otherapparatus. In some aspects, the apparatus may include means forreceiving location information for the other apparatus, wherein thedetermination of whether to send the updated set of handoff entries maybe further based on the location information. In some aspects, theapparatus may include: means for receiving location information for theother apparatus; and means for determining movement of the otherapparatus based on the location information, wherein the determinationof whether to send the updated set of handoff entries may be furtherbased on the movement of the other apparatus. In some aspects, theapparatus may include: means for receiving location information for theother apparatus; means for determining movement of the other apparatusbased on the location information; and means for determining how manyupdated handoff entries to send based on the movement of the otherapparatus.

In one aspect, the disclosure provides a non-transitorycomputer-readable medium storing computer-executable code for anapparatus, including code to: identify a time of validity associatedwith a set of handoff entries, wherein the set of handoff entriesidentifies a set of satellites for handoff of another apparatus;determine, based on the identified time of validity, whether to send anupdated set of handoff entries; and send the updated set of handoffentries if the determination is to send the updated set of handoffentries.

These and other aspects of the disclosure will become more fullyunderstood upon a review of the detailed description, which follows.Other aspects, features, and implementations of the disclosure willbecome apparent to those of ordinary skill in the art, upon reviewingthe following description of specific implementations of the disclosurein conjunction with the accompanying figures. While features of thedisclosure may be discussed relative to certain implementations andfigures below, all implementations of the disclosure can include one ormore of the advantageous features discussed herein. In other words,while one or more implementations may be discussed as having certainadvantageous features, one or more of such features may also be used inaccordance with the various implementations of the disclosure discussedherein. In similar fashion, while certain implementations may bediscussed below as device, system, or method implementations it shouldbe understood that such implementations can be implemented in variousdevices, systems, and methods.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are presented to aid in the description ofaspects of the disclosure and are provided solely for illustration ofthe aspects and not limitations thereof.

The accompanying drawings are presented to aid in the description ofaspects of the disclosure and are provided solely for illustration ofthe aspects and not limitations thereof.

FIG. 1 is a block diagram of an example communication system inaccordance with some aspects of the disclosure.

FIG. 2 is a block diagram of one example of a ground network (GN) ofFIG. 1 in accordance with some aspects of the disclosure.

FIG. 3 is a block diagram of one example of a satellite of FIG. 1 inaccordance with some aspects of the disclosure.

FIG. 4 is a block diagram of one example of a user terminal of FIG. 1 inaccordance with some aspects of the disclosure.

FIG. 5 is a block diagram of one example of a user equipment of FIG. 1in accordance with some aspects of the disclosure.

FIG. 6 is a block diagram illustrating example transmitter and receiverdevices in accordance with some aspects of the disclosure.

FIG. 7 is a block diagram of an example communication system inaccordance with some aspects of the disclosure.

FIG. 8 is a diagram illustrating an example of communicating idle modeinformation in accordance with some aspects of the disclosure.

FIG. 9 is a diagram illustrating an example of idle mode handoff inaccordance with some aspects of the disclosure.

FIG. 10 is a block diagram of an example communication system inaccordance with some aspects of the disclosure.

FIG. 11 is a diagram illustrating an example of inter-satellite handoffsignaling in accordance with some aspects of the disclosure.

FIG. 12 is a diagram illustrating another example of inter-satellitehandoff signaling in accordance with some aspects of the disclosure.

FIG. 13 is a diagram illustrating an example of feeder link switching inaccordance with some aspects of the disclosure.

FIG. 14 is a diagram illustrating an example of a satellite pointingerror in accordance with some aspects of the disclosure.

FIG. 15 is a diagram illustrating an example of a call flow for anon-random access-based B×P handoff in accordance with some aspects ofthe disclosure.

FIG. 16 is a diagram illustrating an example of a call flow for anon-random access-based B×P handoff with user terminal (UT) measurementsin accordance with some aspects of the disclosure.

FIG. 17 is a diagram illustrating an example of a call flow for a randomaccess-based B×P handoff in accordance with some aspects of thedisclosure.

FIGS. 18 and 19 are diagrams illustrating an example of a call flow fora random access-based B×P handoff with UT measurements in accordancewith some aspects of the disclosure.

FIGS. 20, 21, and 22 are diagrams illustrating an example of a call flowfor an A×P handoff in accordance with some aspects of the disclosure.

FIG. 23 is a diagram illustrating an example of a call flow for radiolink failure in accordance with some aspects of the disclosure.

FIG. 24 is a diagram illustrating an example of generating and using asatellite and cell transition table in accordance with some aspects ofthe disclosure.

FIG. 25 is a diagram illustrating an example of using a satellite andcell transition table in accordance with some aspects of the disclosure.

FIG. 26 is a diagram illustrating an example of signaling user terminalcapabilities in accordance with some aspects of the disclosure.

FIG. 27 is a diagram illustrating an example of using user terminalcapabilities in accordance with some aspects of the disclosure.

FIG. 28 is a diagram illustrating an example of signaling user terminallocation information in accordance with some aspects of the disclosure.

FIG. 29 is a diagram illustrating an example of using user terminallocation information in accordance with some aspects of the disclosure.

FIG. 30 is a diagram illustrating an example of user terminal handoffoperations in accordance with some aspects of the disclosure.

FIG. 31 is a diagram illustrating an example of GN handoff operations inaccordance with some aspects of the disclosure.

FIG. 32 is a diagram illustrating another example of inter-satellitehandoff signaling in accordance with some aspects of the disclosure.

FIG. 33 is a diagram illustrating an example of signaling ephemerisinformation in accordance with some aspects of the disclosure.

FIG. 34 is a diagram illustrating an example of radio link failureoperations in accordance with some aspects of the disclosure.

FIG. 35 is a diagram illustrating an example of measurement gap-relatedoperations in accordance with some aspects of the disclosure.

FIG. 36 is a diagram illustrating another example of measurementgap-related operations in accordance with some aspects of thedisclosure.

FIG. 37 is a diagram illustrating an example of user queue-relatedoperations in accordance with some aspects of the disclosure.

FIG. 38 is a diagram illustrating an example of random access-relatedoperations in accordance with some aspects of the disclosure.

FIG. 39 is a block diagram illustrating an example hardwareimplementation for an apparatus (e.g., an electronic device) that cansupport communication in accordance with some aspects of the disclosure.

FIG. 40 is a flowchart illustrating an example communication process inaccordance with some aspects of the disclosure.

FIG. 41 is a flowchart illustrating an example communication process inaccordance with some aspects of the disclosure.

FIG. 42 is a flowchart illustrating an example communication process inaccordance with some aspects of the disclosure.

FIG. 43 is a block diagram illustrating an example hardwareimplementation for an apparatus (e.g., an electronic device) that cansupport communication in accordance with some aspects of the disclosure.

FIG. 44 is a flowchart illustrating an example communication process inaccordance with some aspects of the disclosure.

FIG. 45 is a flowchart illustrating an example communication process inaccordance with some aspects of the disclosure.

FIG. 46 is a block diagram illustrating an example hardwareimplementation for an apparatus (e.g., an electronic device) that cansupport satellite-related communication in accordance with some aspectsof the disclosure.

FIG. 47 is a flowchart illustrating an example of a process involvinggeneration of satellite handoff information in accordance with someaspects of the disclosure.

FIG. 48 is a flowchart illustrating an example of a process involvinggeneration of satellite and cell transition information in accordancewith some aspects of the disclosure.

FIG. 49 is a block diagram illustrating an example hardwareimplementation for another apparatus (e.g., an electronic device) thatcan support satellite-related communication in accordance with someaspects of the disclosure.

FIG. 50 is a flowchart illustrating an example of a process involvinghandoff in accordance with some aspects of the disclosure.

FIG. 51 is a flowchart illustrating an example of a process involvinghandoff in accordance with some aspects of the disclosure.

DETAILED DESCRIPTION

Various aspects of the disclosure relate to idle mode handoff for a userterminal (UT). In some scenarios, an idle UT requests idle mode handoffinformation from a ground network (GN). The idle mode handoffinformation may include, for example, start times for a set ofsatellites, whereby each particular start time indicates when the idleUT may handoff to the corresponding satellite. In some aspects, the idleUT may send the request for idle mode handoff information to the GN whenthe idle UT has a defined number of valid entries (e.g., one unexpiredentry) remaining in an idle mode handoff table. In some aspects, theidle UT may send the request for idle mode handoff information to the GNbased on a time associated with a particular entry (e.g., the lastentry) in an idle mode handoff table. In some aspects, the idle UT maysend the request for idle mode handoff information to the GN based on atime of validity of an idle mode handoff table. In some aspects, theidle UT may send the request for idle mode handoff information to the GNwhen the idle UT establishes a Radio connection with the GN. In someaspects, the GN may autonomously (e.g., without a request from the idleUT) send idle mode handoff information to the idle UT when the idle UTestablishes a Radio connection with the GN.

Aspects of the disclosure are described in the following description andrelated drawings directed to specific examples. Alternate examples maybe devised without departing from the scope of the disclosure.Additionally, well-known elements will not be described in detail orwill be omitted so as not to obscure the relevant details of thedisclosure.

FIG. 1 illustrates an example of a satellite communication system 100which includes a plurality of satellites (although only one satellite300 is shown for clarity of illustration) in non-geosynchronous orbits,for example, low-earth orbits (LEO), a ground network 200 (e.g.,corresponding to a satellite gateway or a satellite network portal) incommunication with the satellite 300, a plurality of UTs 400 and 401 incommunication with the satellite 300, and a plurality of user equipment(UE) 500 and 501 in communication with the UTs 400 and 401,respectively. Each UE 500 or 501 may be a user device such as a mobiledevice, a telephone, a smartphone, a tablet, a laptop computer, acomputer, a wearable device, a smart watch, an audiovisual device, orany device including the capability to communicate with a UT.Additionally, the UE 500 and/or the UE 501 may be a device (e.g., accesspoint, small cell, etc.) that is used to communicate to one or more enduser devices. In the example illustrated in FIG. 1, the UT 400 and theUE 500 communicate with each other via a bidirectional access link(having a forward access link and a return access link), and similarly,the UT 401 and the UE 501 communicate with each other via anotherbidirectional access link. In another implementation, one or moreadditional UEs (not shown) may be configured to receive only andtherefore communicate with a UT only using a forward access link. Inanother implementation, one or more additional UEs (not shown) may alsocommunicate with the UT 400 or the UT 401. Alternatively, a UT and acorresponding UE may be integral parts of a single physical device, suchas a mobile telephone with an integral satellite transceiver and anantenna for communicating directly with a satellite, for example.

The GN 200 may have access to the Internet 108 or one or more othertypes of public, semiprivate or private networks. In the exampleillustrated in FIG. 1, the GN 200 is in communication withinfrastructure 106, which is capable of accessing the Internet 108 orone or more other types of public, semiprivate or private networks. TheGN 200 may also be coupled to various types of communication backhaul,including, for example, landline networks such as optical fiber networksor public switched telephone networks (PSTN) 110. Further, inalternative implementations the GN 200 may interface to the Internet108, PSTN 110, or one or more other types of public, semiprivate orprivate networks without using the infrastructure 106. Still further,the GN 200 may communicate with other GNs, such as the GN 201 throughthe infrastructure 106 or alternatively may be configured to communicateto the GN 201 without using the infrastructure 106. The infrastructure106 may include, in whole or part, a network control center (NCC), asatellite control center (SCC), a wired and/or wireless core networkand/or any other components or systems used to facilitate operation ofand/or communication with the satellite communication system 100.

Communication between the satellite 300 and the GN 200 in bothdirections are called feeder links, whereas communication between thesatellite and each of the UTs 400 and 401 in both directions are calledservice links. A signal path from the satellite 300 to a ground station,which may be the GN 200 or one of the UTs 400 and 401, may begenerically called a downlink. A signal path from a ground station tothe satellite 300 may be generically called an uplink. Additionally, asillustrated, signals can have a general directionality such as a forwardlink and a return link (or reverse link). Accordingly, a communicationlink in a direction originating from the GN 200 and terminating at theUT 400 through the satellite 300 is called a forward link, whereas acommunication link in a direction originating from the UT 400 andterminating at the GN 200 through the satellite 300 is called a returnlink or a reverse link. As such, the signal path from the GN 200 to thesatellite 300 is labeled a “Forward Feeder Link” 112 whereas the signalpath from the satellite 300 to the GN 200 is labeled a “Return FeederLink” 114 in FIG. 1. In a similar manner, the signal path from each UT400 or 401 to the satellite 300 is labeled a “Return Service Link” 116whereas the signal path from the satellite 300 to each UT 400 or 401 islabeled a “Forward Service Link” 118 in FIG. 1.

A handoff controller 122 of the UT 401 and a handoff controller 124 ofthe GN 200 cooperate to control handoff of the UT 401 from one satelliteor cell to another. Other components of the satellite communicationsystem 100 may include corresponding handoff controllers as well. Forexample, other GNs, satellites, and UTs (not shown) may include acorresponding controller. However, handoff controllers are onlyillustrated for the UT 401 and the GN 200 to reduce the complexity ofFIG. 1.

The handoff controller 122 of the UT 401 sends UT information (e.g.,including UT location information and/or UT capability information) tothe handoff controller 124 of the GN 200 via the satellite 300 (e.g.,via signaling 126). In addition, the handoff controller 122 includes ahandoff information request controller 136 that determines whether toalso send a handoff information request to the handoff controller 124 ofthe GN 200 (e.g., via signaling 126).

The handoff controller 124 includes a handoff information generator 130that generates handoff information (e.g., a handoff table) indicative ofhandoff timing for the UT 401. In some aspects, the handoff informationgenerator 130 may generate handoff information based, at least in part,on the UT information, satellite locations over time (obtained fromephemeris data), satellite cell patterns, and satellite cell turn-on andturn-off schedules. The handoff controller 124 also includes a handoffinformation sending controller 132 that determines whether to sendhandoff information 134 to the handoff controller 122 via the currentsatellite 300. In some aspects, the handoff information sending control132 may send the handoff information 134 in response to a handoffinformation request from the UT 401.

The handoff controller 122 receives the handoff information 134 via thecurrent satellite 300 and maintains a local copy of handoff information(e.g., a handoff table) 138. The handoff controller 122 can then controlhandoff of the UT 401 based on the handoff information 138.

In some implementations, the satellite communication system 100 managesidle mode handoff information. For example, the handoff controller 124may determine (e.g., generate) the idle mode handoff information andsend the idle mode handoff information to the handoff controller 122. Insome aspects, the handoff controller 124 may receive UT information(e.g., UT location information) from the UT 401 and manages its idlemode handoff information based on the UT information. In some aspects,the handoff controller 122 may receive and manage a local copy of idlemode handoff information.

FIG. 2 is an example block diagram of the GN 200, which also can applyto the GN 201 of FIG. 1. The GN 200 is shown to include a number ofantennas 205, an RF subsystem 210, a digital subsystem 220, a PublicSwitched Telephone Network (PSTN) interface 230, a Local Area Network(LAN) interface 240, a GN interface 245, and a GN controller 250. The RFsubsystem 210 is coupled to the antennas 205 and to the digitalsubsystem 220. The digital subsystem 220 is coupled to the PSTNinterface 230, to the LAN interface 240, and to the GN interface 245.The GN controller 250 is coupled to the RF subsystem 210, the digitalsubsystem 220, the PSTN interface 230, the LAN interface 240, and the GNinterface 245.

The RF subsystem 210, which may include a number of RF transceivers 212,an RF controller 214, and an antenna controller 216, may transmitcommunication signals to the satellite 300 via a forward feeder link301F, and may receive communication signals from the satellite 300 via areturn feeder link 301R. Although not shown for simplicity, each of theRF transceivers 212 may include a transmit chain and a receive chain.Each receive chain may include a low noise amplifier (LNA) and adown-converter (e.g., a mixer) to amplify and down-convert,respectively, received communication signals in a well-known manner. Inaddition, each receive chain may include an analog-to-digital converter(ADC) to convert the received communication signals from analog signalsto digital signals (e.g., for processing by the digital subsystem 220).Each transmit chain may include an up-converter (e.g., a mixer) and apower amplifier (PA) to up-convert and amplify, respectively,communication signals to be transmitted to the satellite 300 in awell-known manner. In addition, each transmit chain may include adigital-to-analog converter (DAC) to convert the digital signalsreceived from the digital subsystem 220 to analog signals to betransmitted to the satellite 300.

The RF controller 214 may be used to control various aspects of a numberof RF transceivers 212 (e.g., selection of the carrier frequency,frequency and phase calibration, gain settings, and the like). Theantenna controller 216 may control various aspects of the antennas 205(e.g., beamforming, beam steering, gain settings, frequency tuning, andthe like).

The digital subsystem 220 may include a number of digital receivermodules 222, a number of digital transmitter modules 224, a baseband(BB) processor 226, and a control (CTRL) processor 228. The digitalsubsystem 220 may process communication signals received from the RFsubsystem 210 and forward the processed communication signals to thePSTN interface 230 and/or the LAN interface 240, and may processcommunication signals received from the PSTN interface 230 and/or theLAN interface 240 and forward the processed communication signals to theRF subsystem 210.

Each digital receiver module 222 may correspond to signal processingelements used to manage communication between the GN 200 and the UT 400.One of the receive chains of RF transceivers 212 may provide inputsignals to multiple digital receiver modules 222. A number of digitalreceiver modules 222 may be used to accommodate all of the satellitebeams and possible diversity mode signals being handled at any giventime. Although not shown for simplicity, each digital receiver module222 may include one or more digital data receivers, a searcher receiver,and a diversity combiner and decoder circuit. The searcher receiver maybe used to search for appropriate diversity modes of carrier signals,and may be used to search for pilot signals (or other relatively fixedpattern strong signals).

The digital transmitter modules 224 may process signals to betransmitted to the UT 400 via the satellite 300. Although not shown forsimplicity, each digital transmitter module 224 may include a transmitmodulator that modulates data for transmission. The transmission powerof each transmit modulator may be controlled by a corresponding digitaltransmit power controller (not shown for simplicity) that may (1) applya minimum level of power for purposes of interference reduction andresource allocation and (2) apply appropriate levels of power whenneeded to compensate for attenuation in the transmission path and otherpath transfer characteristics.

The control processor 228, which is coupled to the digital receivermodules 222, the digital transmitter modules 224, and the basebandprocessor 226, may provide command and control signals to effectfunctions such as, but not limited to, signal processing, timing signalgeneration, power control, handoff control, diversity combining, andsystem interfacing.

The control processor 228 may also control the generation and power ofpilot, synchronization, and paging channel signals and their coupling tothe transmit power controller (not shown for simplicity). The pilotchannel is a signal that is not modulated by data, and may use arepetitive unchanging pattern or non-varying frame structure type(pattern) or tone type input. For example, the orthogonal function usedto form the channel for the pilot signal generally has a constant value,such as all 1's or 0's, or a well-known repetitive pattern, such as astructured pattern of interspersed 1's and 0's.

The baseband processor 226 is well known in the art and is therefore notdescribed in detail herein. For example, the baseband processor 226 mayinclude a variety of known elements such as (but not limited to) coders,data modems, and digital data switching and storage components.

The PSTN interface 230 may provide communication signals to, and receivecommunication signals from, an external PSTN either directly or throughadditional infrastructure 106, as illustrated in FIG. 1. The PSTNinterface 230 is well known in the art, and therefore is not describedin detail herein. For other implementations, the PSTN interface 230 maybe omitted, or may be replaced with any other suitable interface thatconnects the GN 200 to a ground-based network (e.g., the Internet).

The LAN interface 240 may provide communication signals to, and receivecommunication signals from, an external LAN. For example, the LANinterface 240 may be coupled to the Internet 108 either directly orthrough additional infrastructure 106, as illustrated in FIG. 1. The LANinterface 240 is well known in the art, and therefore is not describedin detail herein.

The GN interface 245 may provide communication signals to, and receivecommunication signals from, one or more other GNs associated with thesatellite communication system 100 of FIG. 1 (and/or to/from GNsassociated with other satellite communication systems, not shown forsimplicity). For some implementations, the GN interface 245 maycommunicate with other GNs via one or more dedicated communication linesor channels (not shown for simplicity). For other implementations, theGN interface 245 may communicate with other GNs using the PSTN 110and/or other networks such as the Internet 108 (see also FIG. 1). For atleast one implementation, the GN interface 245 may communicate withother GNs via the infrastructure 106.

Overall GN control may be provided by the GN controller 250. The GNcontroller 250 may plan and control utilization of the satellite 300'sresources by the GN 200. For example, the GN controller 250 may analyzetrends, generate traffic plans, allocate satellite resources, monitor(or track) satellite positions, and monitor the performance of the GN200 and/or the satellite 300. The GN controller 250 may also be coupledto a ground-based satellite controller (not shown for simplicity) thatmaintains and monitors orbits of the satellite 300, relays satelliteusage information to the GN 200, tracks the positions of the satellite300, and/or adjusts various channel settings of the satellite 300.

For the example implementation illustrated in FIG. 2, the GN controller250 includes local time, frequency, and position references 251, whichmay provide local time or frequency information to the RF subsystem 210,the digital subsystem 220, and/or the interfaces 230, 240, and 245. Thetime or frequency information may be used to synchronize the variouscomponents of the GN 200 with each other and/or with the satellite(s)300. The local time, frequency, and position references 251 may alsoprovide position information (e.g., ephemeris data) of the satellite(s)300 to the various components of the GN 200. Further, although depictedin FIG. 2 as included within the GN controller 250, for otherimplementations, the local time, frequency, and the position references251 may be a separate subsystem that is coupled to the GN controller 250(and/or to one or more of the digital subsystem 220 and the RF subsystem210).

Although not shown in FIG. 2 for simplicity, the GN controller 250 mayalso be coupled to a network control center (NCC) and/or a satellitecontrol center (SCC). For example, the GN controller 250 may allow theSCC to communicate directly with the satellite(s) 300, for example, toretrieve ephemeris data from the satellite(s) 300. The GN controller 250may also receive processed information (e.g., from the SCC and/or theNCC) that allows the GN controller 250 to properly aim its antennas 205(e.g., at the appropriate satellite(s) 300), to schedule beamtransmissions, to coordinate handoffs, and to perform various otherwell-known functions.

The GN controller 250 may include one or more of a processing circuit232, a memory device 234, or a handoff controller 236 that independentlyor cooperatively perform handoff information-related operations for theGN 200 as taught herein. In an example implementation, the processingcircuit 232 is configured (e.g., programmed) to perform some or all ofthese operations. In another example implementation, the processingcircuit 232 (e.g., in the form of a processor) executes code stored inthe memory device 234 to perform some or all of these operations. Inanother example implementation, the handoff controller 236 is configured(e.g., programmed) to perform some or all of these operations. Althoughdepicted in FIG. 2 as included within the GN controller 250, for otherimplementations, one or more of the processing circuit 232, the memorydevice 234, or the handoff controller 236 may be a separate subsystemthat is coupled to the GN controller 250 (and/or to one or more of thedigital subsystem 220 and the RF subsystem 210).

FIG. 3 is an example block diagram of the satellite 300 for illustrativepurposes only. It will be appreciated that specific satelliteconfigurations can vary significantly and may or may not includeon-board processing. Further, although illustrated as a singlesatellite, two or more satellites using inter-satellite communicationmay provide the functional connection between the GN 200 and the UT 400.It will be appreciated that the disclosure is not limited to anyspecific satellite configuration and any satellite or combinations ofsatellites that can provide the functional connection between the GN 200and UT 400 can be considered within the scope of the disclosure. In oneexample, the satellite 300 is shown to include a forward transponder310, a return transponder 320, an oscillator 330, a controller 340,forward link antennas 351 and 352(1)-352(N), and return link antennas362 and 361(1)-361(N). The forward transponder 310, which may processcommunication signals within a corresponding channel or frequency band,may include a respective one of first bandpass filters 311(1)-311(N), arespective one of first low noise amplifiers (LNAs) 312(1)-312(N), arespective one of frequency converters 313(1)-313(N), a respective oneof second LNAs 314(1)-314(N), a respective one of second bandpassfilters 315(1)-315(N), and a respective one of power amplifiers (PAs)316(1)-316(N). Each of the PAs 316(1)-316(N) is coupled to a respectiveone of antennas 352(1)-352(N), as shown in FIG. 3.

Within each of respective forward paths FP(1)-FP(N), the first bandpassfilter 311 passes signal components having frequencies within thechannel or frequency band of the respective forward path FP, and filterssignal components having frequencies outside the channel or frequencyband of the respective forward path FP. Thus, the pass band of the firstbandpass filter 311 corresponds to the width of the channel associatedwith the respective forward path FP. The first LNA 312 amplifies thereceived communication signals to a level suitable for processing by thefrequency converter 313. The frequency converter 313 converts thefrequency of the communication signals in the respective forward path FP(e.g., to a frequency suitable for transmission from the satellite 300to the UT 400). The second LNA 314 amplifies the frequency-convertedcommunication signals, and the second bandpass filter 315 filters signalcomponents having frequencies outside of the associated channel width.The PA 316 amplifies the filtered signals to a power level suitable fortransmission to the UTs 400 via a respective antenna 352. The returntransponder 320, which includes a number N of return paths RP(1)-RP(N),receives communication signals from the UT 400 along the return servicelink 302R via the antennas 361(1)-361(N), and transmits communicationsignals to the GN 200 along the return feeder link 301R via one or moreof the antennas 362. Each of the return paths RP(1)-RP(N), which mayprocess communication signals within a corresponding channel orfrequency band, may be coupled to a respective one of the antennas361(1)-361(N), and may include a respective one of first bandpassfilters 321(1)-321(N), a respective one of first LNAs 322(1)-322(N), arespective one of frequency converters 323(1)-323(N), a respective oneof second LNAs 324(1)-324(N), and a respective one of second bandpassfilters 325(1)-325(N).

Within each of the respective return paths RP(1)-RP(N), the firstbandpass filter 321 passes signal components having frequencies withinthe channel or frequency band of the respective return path RP, andfilters signal components having frequencies outside the channel orfrequency band of the respective return path RP. Thus, the pass band ofthe first bandpass filter 321 may for some implementations correspond tothe width of the channel associated with the respective return path RP.The first LNA 322 amplifies all the received communication signals to alevel suitable for processing by the frequency converter 323. Thefrequency converter 323 converts the frequency of the communicationsignals in the respective return path RP (e.g., to a frequency suitablefor transmission from the satellite 300 to the GN 200). The second LNA324 amplifies the frequency-converted communication signals, and thesecond bandpass filter 325 filters signal components having frequenciesoutside of the associated channel width. Signals from the return pathsRP(1)-RP(N) are combined and provided to the one or more antennas 362via a PA 326. The PA 326 amplifies the combined signals for transmissionto the GN 200.

The oscillator 330, which may be any suitable circuit or device thatgenerates an oscillating signal, provides a forward local oscillatorsignal LO(F) to the frequency converters 313(1)-313(N) of the forwardtransponder 310, and provides a return local oscillator signal LO(R) tothe frequency converters 323(1)-323(N) of the return transponder 320.For example, the LO(F) signal may be used by the frequency converters313(1)-313(N) to convert communication signals from a frequency bandassociated with the transmission of signals from the GN 200 to thesatellite 300 to a frequency band associated with the transmission ofsignals from the satellite 300 to the UT 400. The LO(R) signal may beused by the frequency converters 323(1)-323(N) to convert communicationsignals from a frequency band associated with the transmission ofsignals from the UT 400 to the satellite 300 to a frequency bandassociated with the transmission of signals from the satellite 300 tothe GN 200.

The controller 340, which is coupled to the forward transponder 310, thereturn transponder 320, and the oscillator 330, may control variousoperations of the satellite 300 including (but not limited to) channelallocations. In one aspect, the controller 340 may include a processingcircuit 364 (e.g., a processor) coupled to a memory (e.g., a memorydevice 366). The memory may include a non-transitory computer-readablemedium (e.g., one or more nonvolatile memory elements, such as an EPROM,an EEPROM, a Flash memory, a hard drive, etc.) storing instructionsthat, when executed by the processing circuit 364, cause the satellite300 to perform operations including (but not limited to) those describedherein.

FIG. 4 is an example block diagram of the UT 400 or the UT 401 forillustrative purposes only. It will be appreciated that specific UTconfigurations can vary significantly. Thus, the disclosure is notlimited to any specific UT configuration and any UT that can provide thefunctional connection between the satellite 300 and the UE 500 or 501can be considered within the scope of the disclosure.

UTs may be used in various applications. In some scenarios, a UT mayprovide a cellular backhaul. In this case, the UT may have a relativelylarge antenna and/or multiple antennas (e.g., to protect againstblockage). In some scenarios, a UT may be deployed in an enterpriseenvironment (e.g., placed on the roof of a building). In this case, theUT may have a relatively large antenna and/or multiple antennas (e.g.,to provide relatively high backhaul bandwidth). In some scenarios, a UTmay be deployed in a residential environment (e.g., placed on the roofof a house). In this case, the UT may have a smaller (and relativelyinexpensive) antenna and provide fixed access for data service (e.g.,Internet access). In some scenarios, a UT may be deployed in a maritimeenvironment (e.g., placed on a cruise ship, a cargo ship, etc.). In thiscase, the UT may have a relatively large antenna and/or multipleantennas (e.g., to prevent blockage and provide relatively highbandwidth data service). In some scenarios, a UT may be deployed on avehicle (e.g., carried by first responders, emergency crews, etc.). Inthis case, the UT may have a smaller antenna and used to providetemporary Internet access to a particular area (e.g., where cellularservice is out). Other scenarios are possible.

The configuration of a particular UT may depend on the application forwhich the UT will be used. For example, the type of antenna, the antennashape, the quantity of antennas, the supported bandwidth, the supportedtransmit power, the receiver sensitivity, etc., may depend on thecorresponding application. As one example, a flat panel antenna (with arelatively low profile) may be used for aircraft applications.

In the example of FIG. 4, the UT is shown to include a transceiver whereat least one antenna 410 is provided for receiving forward linkcommunication signals (e.g., from the satellite 300), which aretransferred to an analog receiver 414, where they are down-converted,amplified, and digitized. A duplexer element 412 is often used to allowthe same antenna to serve both transmit and receive functions.Alternatively, a UT transceiver may employ separate antennas foroperating at different transmit and receive frequencies.

The digital communication signals output by the analog receiver 414 aretransferred to at least one digital data receiver 416A and at least onesearcher receiver 418. Additional digital data receivers (e.g., asrepresented by a digital data receiver 416N) can be used to obtaindesired levels of signal diversity, depending on the acceptable level oftransceiver complexity, as would be apparent to one skilled in therelevant art.

At least one user terminal control processor 420 is coupled to thedigital data receivers 416A-416N and the searcher receiver 418. Thecontrol processor 420 provides, among other functions, basic signalprocessing, timing, power and handoff control or coordination, andselection of frequency used for signal carriers. Another basic controlfunction that may be performed by the control processor 420 is theselection or manipulation of functions to be used for processing varioussignal waveforms. Signal processing by the control processor 420 caninclude a determination of relative signal strength and computation ofvarious related signal parameters. Such computations of signalparameters, such as timing and frequency may include the use ofadditional or separate dedicated circuitry to provide increasedefficiency or speed in measurements or improved allocation of controlprocessing resources.

The outputs of the digital data receivers 416A-416N are coupled todigital baseband circuitry 422 within the UT 400. The digital basebandcircuitry 422 includes processing and presentation elements used totransfer information to and from the UE 500 as shown in FIG. 1, forexample. Referring to FIG. 4, if diversity signal processing isemployed, the digital baseband circuitry 422 may include a diversitycombiner and decoder (not shown). Some of these elements may alsooperate under the control of, or in communication with, a controlprocessor 420.

When voice or other data is prepared as an output message or acommunication signal originating with the UT 400, the digital basebandcircuitry 422 is used to receive, store, process, and otherwise preparethe desired data for transmission. The digital baseband circuitry 422provides this data to a transmit modulator 426 operating under thecontrol of the control processor 420. The output of the transmitmodulator 426 is transferred to a power controller 428 which providesoutput power control to a transmit power amplifier 430 for finaltransmission of the output signal from the antenna 410 to a satellite(e.g., the satellite 300).

In FIG. 4, the UT transceiver also includes a memory 432 associated withthe control processor 420. The memory 432 may include instructions forexecution by the control processor 420 as well as data for processing bythe control processor 420. In the example illustrated in FIG. 4, thememory 432 may include instructions for performing time or frequencyadjustments to be applied to an RF signal to be transmitted by the UT400 via the return service link to the satellite 300.

In the example illustrated in FIG. 4, the UT 400 also includes optionallocal time, frequency and/or position references 434 (e.g., a GPSreceiver), which may provide local time, frequency and/or positioninformation to the control processor 420 for various applications,including, for example, time or frequency synchronization for the UT400.

The digital data receivers 416A-416N and the searcher receiver 418 areconfigured with signal correlation elements to demodulate and trackspecific signals. The searcher receiver 418 is used to search for pilotsignals, or other relatively fixed pattern strong signals, while thedigital data receivers 416A-416N are used to demodulate other signalsassociated with detected pilot signals. However, a digital data receiver416 can be assigned to track the pilot signal after acquisition toaccurately determine the ratio of signal chip energies to signal noise,and to formulate pilot signal strength. Therefore, the outputs of theseunits can be monitored to determine the energy in, or frequency of, thepilot signal or other signals. These receivers also employ frequencytracking elements that can be monitored to provide current frequency andtiming information to the control processor 420 for signals beingdemodulated.

The control processor 420 may use such information to determine to whatextent the received signals are offset from the oscillator frequency,when scaled to the same frequency band, as appropriate. This and otherinformation related to frequency errors and frequency shifts can bestored in a storage or memory element (e.g., the memory 432) as desired.

The control processor 420 may also be coupled to the UE interfacecircuitry 450 to allow communication between the UT 400 and one or moreUEs. The UE interface circuitry 450 may be configured as desired forcommunication with various UE configurations and accordingly may includevarious transceivers and related components depending on the variouscommunication technologies employed to communicate with the various UEssupported. For example, the UE interface circuitry 450 may include oneor more antennas, a wide area network (WAN) transceiver, a wirelesslocal area network (WLAN) transceiver, a Local Area Network (LAN)interface, a Public Switched Telephone Network (PSTN) interface and/orother known communication technologies configured to communicate withone or more UEs in communication with the UT 400.

The control processor 420 may include one or more of a processingcircuit 442, a memory device 444, or a handoff controller 446 thatindependently or cooperatively perform handoff information-relatedoperations for the UT 400 as taught herein. In an exampleimplementation, the processing circuit 442 is configured (e.g.,programmed) to perform some or all of these operations. In anotherexample implementation, the processing circuit 442 (e.g., in the form ofa processor) executes code stored in the memory device 444 to performsome or all of these operations. In another example implementation, thehandoff controller 446 is configured (e.g., programmed) to perform someor all of these operations. Although depicted in FIG. 4 as includedwithin the control processor 420, for other implementations, one or moreof the processing circuit 442, the memory device 444, or the handoffcontroller 446 may be a separate subsystem that is coupled to thecontrol processor 420.

FIG. 5 is a block diagram illustrating an example of the UE 500, whichalso can apply to the UE 501 of FIG. 1. The UE 500 as shown in FIG. 5may be a mobile device, a handheld computer, a tablet, a wearabledevice, a smart watch, or any type of device capable of interacting witha user, for example. Additionally, the UE 500 may be a network sidedevice that provides connectivity to various ultimate end user devicesand/or to various public or private networks. In the example shown inFIG. 5, the UE 500 may include a LAN interface 502, one or more antennas504, a wide area network (WAN) transceiver 506, a wireless local areanetwork (WLAN) transceiver 508, and a satellite positioning system (SPS)receiver 510. The SPS receiver 510 may be compatible with the GlobalPositioning System (GPS), the Global Navigation Satellite System(GLONASS) and/or any other global or regional satellite basedpositioning system. In an alternate aspect, the UE 500 may include aWLAN transceiver 508, such as a Wi-Fi transceiver, with or without theLAN interface 502, the WAN transceiver 506, and/or the SPS receiver 510,for example. Further, the UE 500 may include additional transceiverssuch as Bluetooth, ZigBee and other known technologies, with or withoutthe LAN interface 502, the WAN transceiver 506, the WLAN transceiver 508and/or the SPS receiver 510. Accordingly, the elements illustrated forthe UE 500 are provided merely as an example configuration and are notintended to limit the configuration of UEs in accordance with thevarious aspects disclosed herein.

In the example shown in FIG. 5, a processor 512 is connected to the LANinterface 502, the WAN transceiver 506, the WLAN transceiver 508 and theSPS receiver 510. Optionally, a motion sensor 514 and other sensors mayalso be coupled to the processor 512.

A memory 516 is connected to the processor 512. In one aspect, thememory 516 may include data 518 which may be transmitted to and/orreceived from the UT 400, as shown in FIG. 1. Referring to FIG. 5, thememory 516 may also include stored instructions 520 to be executed bythe processor 512 to perform the process steps for communicating withthe UT 400, for example. Furthermore, the UE 500 may also include a userinterface 522, which may include hardware and software for interfacinginputs or outputs of the processor 512 with the user through light,sound or tactile inputs or outputs, for example. In the example shown inFIG. 5, the UE 500 includes a microphone/speaker 524, a keypad 526, anda display 528 connected to the user interface 522. Alternatively, theuser's tactile input or output may be integrated with the display 528 byusing a touch-screen display, for example. Once again, the elementsillustrated in FIG. 5 are not intended to limit the configuration of theUEs disclosed herein and it will be appreciated that the elementsincluded in the UE 500 will vary based on the end use of the device andthe design choices of the system engineers.

Additionally, the UE 500 may be a user device such as a mobile device orexternal network side device in communication with but separate from theUT 400 as illustrated in FIG. 1, for example. Alternatively, the UE 500and the UT 400 may be integral parts of a single physical device.

In the example shown in FIG. 1, the two UTs 400 and 401 may conducttwo-way communication with the satellite 300 via return and forwardservice links within a beam coverage. A satellite may communicate withmore than two UTs within a beam coverage. The return service link fromthe UTs 400 and 401 to the satellite 300 may thus be a many-to-onechannel. Some of the UTs may be mobile while others may be stationary,for example. In a satellite communication system such as the exampleillustrated in FIG. 1, multiple UTs 400 and 401 within a beam coveragemay be time-division-multiplexed (TDM'ed),frequency-division-multiplexed (FDM'ed), or both.

UT Handoff

At some point in time, a UT may need to be handed-off to anothersatellite (not shown in FIG. 1). Handoff may be caused by scheduledevents or unscheduled events.

Several examples of handoff due to scheduled events follow. Inter-beamand inter-satellite handoff may be caused by movement of the satellite,movement of the UT, or a satellite beam being turned off (e.g., due to aGeo-stationary satellite (GEO) restriction). Handoff also may be due toa satellite moving out of the GN's range while the satellite is stillwithin the UT's line of sight.

Several examples of handoff due to nonscheduled events follow. Handoffmay be triggered by a satellite being obscured by an obstacle (e.g., atree). Handoff also may be triggered due to a drop in channel quality(e.g., signal quality) due to rain fade or other atmospheric conditions.

In some implementations, at a particular point in time, a particularsatellite may be controlled by a particular entity (e.g., a networkaccess controller, NAC) in a GN. Thus, a GN may have several NACs (e.g.,implemented by the GN controller 250 of FIG. 2), each of which controlsa corresponding one of the satellites controlled by the GN. In addition,a given satellite may support multiple beams. Thus, over time, differenttypes of handoff may occur.

In inter-beam handoff, a UT is handed-off from one beam of a satelliteto another beam of the satellite. For example, the particular beamserving a stationary UT may change over time as the serving satellitemoves.

In inter-satellite handoff, a UT is handed-off from the current servingsatellite (referred to as the source satellite) to another satellite(referred to as the target satellite). For example, a UT may behanded-off to the target satellite as the source satellite moves awayfrom the UT and the target satellite moves toward the UT.

Idle Mode Handoff

In a satellite network, a UT in idle mode should point to the bestsatellite and beam to receive a page for the idle UT. Similarly, the GNshould use the same satellite beam to page the idle UT. In practice, theselection of the correct satellite and beam may be challenging (e.g.,relatively complex) since the satellites and beams may be turned off fora variety of reasons that are known to the GN but not to the idle UT.Consequently, it is possible that an idle UT could point to a differentsatellite than the GN uses to page the idle UT.

To address this issue, the disclosure relates in some aspects to anetwork-guided idle mode handoff procedure that enables an idle UT toreliably receive paging messages transmitted by the GN. To receive apage, an idle UT identifies and points its antenna at the satellite thatwill be providing coverage for the idle UT at that time. This enablesthe idle UT to then tune to a beam that the satellite will betransmitting in, camp on the corresponding cell, and monitor the controlchannel to determine whether there is a page for the idle UT.

In some aspects, the network-guided idle mode handoff algorithm involvesthe GN repeatedly (e.g., periodically or aperiodically) or on demandproviding to the idle UT information that the UT can use to performhandoff (reselection) when the UT is in idle mode. This information maybe referred to as idle mode information. The UT may maintain thisinformation in an idle mode handoff table.

The idle mode information may take various forms. In some cases, theidle mode information indicates the sequence of satellites that will becovering the idle UT over a span of time, such that the idle UT cansubsequently point to the correct satellite and receive a page (e.g., atdesignated times). In some cases, the idle mode information includesstart times for a set of satellites, where each particular start timeindicates when the idle UT may handoff to the corresponding satellite.Thus, the application relates in some aspects to network-guided idlereselection where a UT is directed by the network to a proper list ofsatellites for idle mode operation.

In some scenarios, an idle UT requests idle mode handoff informationfrom a GN. In some scenarios, an idle UT may send a request for idlemode handoff information to the GN when the idle UT has a defined numberof valid entries remaining in an idle mode handoff table. For example,the idle UT may send the request when there is only one unexpired entryremaining in the table. In some scenarios, an idle UT may send a requestfor idle mode handoff information to the GN if the idle mode handofftable is about to expire or has expired. In some scenarios, an idle UTmay send a request for idle mode handoff information to the GN based ona time associated with a particular entry (e.g., the last entry) of theidle mode handoff table.

The request may include, for example, the start time of the last entryin the current idle mode handoff table at the UT and the location of theUT. This information enables the GN to determine the next set ofsatellites that will be covering the idle UT and to determine when tosend an indication of the next set of satellite to the UT.

In some scenarios, a GN may send idle mode information to a UT duringradio connection operations. For example, an idle UT may send a requestfor idle mode handoff information to the GN when the idle UT establishesa radio connection with the GN. As another example, the GN mayautonomously (e.g., without a request from the idle UT) send idle modehandoff information to the idle UT when the idle UT establishes a radioconnection with the GN.

Example Handoff Signaling

The disclosure relates in some aspects to signaling to support idle modehandoff. FIG. 6 illustrates a communication system 600 that includes afirst apparatus 602 and a second apparatus 604. The first apparatus 602maintains (e.g., generates) idle mode handoff information (e.g., atable) 606 and includes a transmitter 608 that can transmit idle modehandoff information 610 to the second apparatus 604. The secondapparatus 604 includes a receiver 612 for receiving the idle modehandoff information 610 such that the second apparatus 604 can maintainlocal idle mode handoff information 614. In some aspects, the firstapparatus 602 may be an example of the GN 200 or the GN 201 of FIG. 1.In addition, the second apparatus 604 may be an example of the UT 400 orthe UT 401 of FIG. 1.

In some implementations, the communication system 600 is a satellitecommunication system. FIG. 7 illustrates a UT 702 in communication witha GN 704 via a satellite 706 in a non-geosynchronous satellitecommunication system 700, such as a LEO satellite communication systemfor data, voice, video, or other communication. The UT 702, the GN 704,and the satellite 706 may respectively correspond to, for example, theUT 401, the GN 200, and the satellite 300 of FIG. 1.

The GN 704 includes network access controllers (NACs) 712, each of whichinterfaces with one or more radio frequency (RF) subsystems 714 forcommunicating with the UT 702 and other UTs (not shown) via thesatellite 706 (or some other satellite, not shown). The GN 704 alsoincludes a core network control plane (CNCP) 716 and a core network userplane (CNUP) 718, or other similar functionality, for communicating withanother network 720. The network 720 may represent, for example, one ormore of a core network (e.g., 3G, 4G, 5G, etc.), an intranet, or theInternet.

At various points in time, the GN 704 may determine (e.g., receive orgenerate) idle mode handoff information 722. The GN may then broadcastor unicast the idle mode handoff information 722 to the UT 702 viamessages 724 and 726 relayed by the satellite 706. The UT 702 therebymaintains its own idle mode handoff information 728. The GN 704 may sendthe idle mode handoff information 722 to the UT in response to a requestfrom the UT or autonomously (e.g., not in response to a request).

In an example implementation, a request for an idle mode handoff tablemay include two fields. A first field includes a start time (e.g.,absolute GPS time) of the last row entry of the current table. The starttime may be set to 0 if the UT does not have a current table. This firstfield could be 32 bits or some other size. A second field includes thelocation of the UT corresponding to the last received table (e.g., thisfield could be used for moving UTs only). This field could be 32 bits orsome other size. In some implementations, the request could also include(e.g., in another field) an indication of the time of validity of thecurrent idle mode handoff table at the UT (e.g., an indication of howmuch longer the table is valid).

The disclosure relates in some aspects to using a unicastsignaling-based transfer of idle mode handoff information (e.g., an idlemode handoff table). In some aspects, unicast signaling may provide moreflexibility than broadcast information block-based idle mode updates(e.g., unicast signaling may be more adaptable for future development).

FIG. 8 illustrates an example of signaling call-flow 800 to providehandoff information (e.g., a handoff table) to an idle UT. The signalingcall-flow 800 includes a request-response pair of Radio messages thatmay be based, for example, on a network-guided idle mode handoffalgorithm.

In some aspects, the request-response pair of messages may be exchangedbetween a UT 802 and a GN 804 when the UT is Radio connected and whensecurity is active 806. That is, Radio request-response messages may beused to provide an idle mode handoff table to a UT that is Radioconnected, and the table may be provided after security is activated.

An idle mode handoff table request message 808 may be sent after (or canbe sent simultaneously when) UT location information is sent. Forexample, the request message 808 can be provided simultaneously with aRadio UT location report message 810.

In some aspects, the GN may use the UT location information to preparean idle mode handoff table for the UT. For example, the GN maydetermine, based on satellite ephemeris information and the UT'slocation, which satellites may be able to serve the UT over a givenperiod of time. The GN then sends an idle mode handoff table responsemessage 812 including this satellite information to the UT and the UTupdates its table 814.

In some implementations, the GN may determine whether the send an idlemode handoff table to the UT based on the time of validity of thecurrent idle mode handoff table at the UT. In some cases, the GN mayreceive an indication of this time of validity from the UT (e.g., in anidle mode handoff table request message). In some cases, the GN maytrack this time of validity by itself (e.g., based on a validity timethe GN calculates for the last table the GN sent to the UT).

In some implementations, the GN may determine whether to send an idlemode handoff table to the UT based on a time (e.g., a start time)associated with an entry (e.g., the last entry) of the current idle modehandoff table at the UT. In some cases, the GN may receive an indicationof this time from the UT (e.g., in a handoff table request message). Insome cases, the GN may track this time by itself (e.g., by saving thelast table the GN sent to the UT).

In view of the above, the disclosure relates in some aspects to sendingto a UT an indication of at least one satellite for an idle modeoperation of the UT. Here, the indication of at least one satellite maytake the form of a satellite table, a satellite list, or some otherform. For each satellite of the at least one satellite (e.g., in asatellite list), an indication may also be sent to the UT indicating thetime that the UT is to handoff to the satellite. An indication of atleast one carrier frequency at which the next satellite cell (e.g., thecell of the next satellite that will be serving the UT) will betransmitting may also be sent to the UT.

In some aspects, a decision to send the indication may be based on: 1)the location of the UT; 2) the start time for an entry (e.g., the lastentry) in the current idle mode handoff table; 3) the number of validentries in the idle mode handoff table; or 4) a combination thereof. Insome aspects, a decision to send the indication may be based on the timeof validity of the last idle mode handoff table a GN provided to the UT.The above information enables a GN to determine whether the UT is aboutto run out of current satellite information. Consequently, a GN may senda new table to the UT if the last table sent to the UT is about to runout of valid entries or if the table is about to expire.

Example Handoff Table

A GN may send idle mode handoff information (e.g., autonomously or inresponse to a request) via an idle mode handoff table. An example idlemode handoff table is shown in Table 1. The base time for the table(e.g., in seconds) may be, for example: absolute GPS time (e.g., 32bits). This table would be updated over time (e.g., as the satellitesmove and/or the UT moves). It should be appreciated that differenthandoff tables may include different types of information and/ordifferent entries.

TABLE 1 Satellite ID Start Times (e.g., seconds) Sat1 startTime1 outagestartTime2 Sat3 startTime3 . . . . . . SatN startTimeN

In an example implementation, a handoff table may include the threefields that follow. A first field is for the base time for the table(e.g., in seconds): absolute GPS time (e.g., 32 bits). A second field isfor the Satellite ID (e.g., 16 bits). Table 1 shows an example of thisfield. The second field could also indicate outage periods when nosatellite is covering the UT (e.g., due to EPFD mitigation), as shown. Athird field is for start times: startTime 1, . . . , startTimeN. (e.g.,each 32 bits). Table 1 also shows an example of this field. These timesmay be chosen such that the GN can specify long enough periods of timerelative to the base time during which the table entries are valid.

The size of the handoff table provided to the UT may depend on whetherthe UT is stationary or moving. In general, smaller handoff tables maybe used for moving UTs whereby the size of such a handoff table maydepend on the speed at which a UT is moving.

For fast moving UTs (e.g., UTs on an airplane), a smaller table may beprovided because the table may be invalidated quickly due to UT motion.Such a table may be valid, for example, for a few minutes.

For slow moving UTs (e.g., UTs on a cruise ship or a container ship), alarger table may be provided. Such a table may be valid, for example,for an hour.

For a stationary UT, a large table can be provided to reduce theoverhead due to establishment of a new connection (e.g., as discussed inOption 1 below) or due to signaling overhead (e.g., as discussed in inOption 3 below). Such a table may be valid, for example, for a severalhours (e.g., 10 hours).

A GN can estimate the speed of a UT based on location reports the GNreceives from the UT. Combining this information with the informationreceived in a request message regarding the time for which the currenttable at the UT is valid, the GN can optimize the size of the table thatthe GN provides to a moving UT. This may help achieve a good trade-offbetween the signaling overhead incurred in transmitting a table and theperiod of time for which a provided table can remain valid for a movingUT.

An outage period may exist for different reasons under differentcircumstances. For example, a satellite or satellites may be inactive(e.g., during the period of time that the UT would otherwise be withinthe coverage of the satellite(s)) and thereby unable to provide service.As another example, a service restriction (e.g., a regulatoryrestriction or country restriction) may dictate that a UT cannot receiveservice from a particular satellite (e.g., service is restricted always,at certain times, or at certain locations).

In some aspect, the outage period information may be used by a UT todetermine whether to remain in or enter a low power (e.g., sleep) mode.For example, a UT in or entering idle mode can determine that it maysleep from startTime2 to startTime3 based on Table 1.

Triggers for Requesting or Sending Idle Mode Handoff Information

Various types of triggers could be used to determine when to request orsend idle mode handoff information (e.g., an idle mode handoff table).Several examples of triggers that a UT (or some other type of device)may use to determine when to request idle mode handoff information orthat a GN (or some other type of device) may use to determine when tosend idle mode handoff information follow.

A first request trigger is based on the number of valid entriesremaining in a set of idle mode handoff information (e.g., an idle modehandoff table) maintained by a UT (or some other suitable device). Forexample, a UT may send a request for idle mode handoff information basedon the number of valid entries (e.g., one, two, etc.) that remain in anidle mode handoff table maintained by the UT. As a specific example, aUT may send a request to a GN for idle mode handoff information if theidle mode handoff table only includes one valid entry (or two validentries, or three valid entries, and so on). In this way, the UT canobtain a new idle mode handoff table from the GN before the idle modehandoff table maintained by the UT runs out of valid (e.g., current)entries. In some aspects, an entry in the table may be deemed to beinvalid (e.g., not current) if the time (e.g., the start time, the endtime, etc.) associated with that entry has past.

A second request trigger is based on timing of an entry of a set of idlemode handoff information (e.g., an idle mode handoff table) maintainedby a UT (or some other suitable device). For example, a UT may send arequest for idle mode handoff information based on timing (e.g., a starttime, an end time, etc.) associated with a particular entry (e.g., alast entry, a second to last entry, etc.) of an idle mode handoff tablemaintained by the UT. As a specific example, a UT may send a request toa GN for idle mode handoff information if the difference between thecurrent time and the time (e.g., start time, etc.) for the particularentry (e.g., the last entry) of the idle mode handoff table is less thana threshold amount of time. In this way, the UT can obtain a new idlemode handoff table from the GN before the idle mode handoff tablemaintained by the UT runs out of current entries (e.g., before the tableruns out of entries or is no longer valid).

A third request trigger is based on a combination of the first requesttrigger and the second request trigger. For example, a UT may send arequest to a GN for idle mode handoff information if the idle modehandoff table only includes one valid entry or if the difference betweenthe current time and the time for the last entry is less than athreshold amount of time. Other combinations may be used in otherscenarios.

In some scenarios, the GN (or some other suitable device) may track theUT's table (or some other device's table) to determine when to send idlemode handoff information (e.g., an idle mode handoff table). Such anscenario could occur, for example, in cases where a UT (or some otherdevice) does not send a request for a new table.

A first sending trigger is based on how long the idle mode handoffinformation (e.g., an idle mode handoff table) sent to a UT (or someother suitable device) will remain valid. For example, a GN (or someother suitable device) may send idle mode handoff information to a UTbased on the remaining period of validity for the UT's idle mode handofftable. As a specific example, a GN may send a new idle mode handofftable to a UT if the remaining period of validity for the last idle modehandoff table that the GN sent to the UT is less than a threshold amountof time. In this way, the GN can provide a new idle mode handoff tableto the UT before the UT's idle mode handoff table maintained becomesinvalid.

Other triggers for sending idle mode handoff information may be similarto the first request trigger, the second request trigger, and the thirdrequest trigger. For examples, a GN may send idle mode handoffinformation based on the number of valid entries remaining in a UT'sidle mode handoff table, based on a time (e.g., a start time) for aparticular entry (e.g., the last entry) in a UT's idle mode handofftable, or based on a combination of these triggers.

Example Messages

A GN (or some other suitable device) may sent various types ofinformation to an idle UT (or some other suitable device). In somescenarios, this information may be sent via a broadcast informationblock (BIB) message. In an example implementation this informationindicates at least one carrier frequency (e.g., an absoluteradio-frequency channel number) in which the next cell will betransmitting. This information may be may be carried by a 16 bit (orother size) parameter called “nextCellTransmitFreq.” As one example,nextCellTransmitFreq can indicate a list of possible frequencies thatcan follow. As another example, nextCellTransmitFreq can indicate aparticular frequency. It should be appreciated that nextCellTransmitFreqcould take other forms as well. It may be assumed that a satellite willbe transmitting using a limited number N (e.g., 8 or some other suitablenumber) of carrier frequencies on the forward service link (FSL) over agiven region. The set of N carrier frequencies may vary from region toregion.

A UT may perform the following operations to tune to a beam of asatellite. When the UT switches from one satellite to another followingan idle mode handoff table, the UT may perform a search over the Nfrequencies and select one frequency to camp on. The UT may use thenextCellTransmitFreq information when the UT switches from one beam of asatellite to another beam of the satellite. For example, when the UT isbeing covered by a satellite, the UT may use the nextCellTransmitFreqinformation to determine the next beam to which the UT should tune.

Example Signaling

Several examples of signaling and UT procedures based on the abovefollow. These examples are referred to as Option 1, Option 2, Option 3,and Option 4.

In Option 1, an idle UT sends a request message to the GN when the UThas one entry left in its current table. Here, the UT establishes aRadio connection to the GN and sends the request message. The UT Radiolayer may trigger a control layer to initiate a Service Requestprocedure and establish a Radio connection to a GN. Upon receipt of therequest message, the GN sends a response including a new handoff tableto the UT. The UT replaces its current table with the new table uponreceipt of the response message.

In Option 2, the UT does not send a request message. Instead, the GNmaintains, for each UT, information regarding the time of validity ofthe last table the GN provided to the UT. Whenever the UT establishes aRadio connection to the network, the GN checks whether the UT needs tobe provided a new table and sends a new table if required. In somecases, the GN may send the new table after the GN receives a Radiolocation report message from the UT that indicates the location of theUT.

In Option 3, the UT sends a request message to the GN every time the UTestablishes a Radio connection to the GN. Based on the informationprovided in the request message, the GN determines whether a table needsto be provided to the UT. For example, a stationary UT need not beprovided a new table if the UT has entries for sufficient time into thefuture. For a moving UT, the GN can optimize the size of the table itprovides to the UT based on the information provided in the requestmessage (e.g., as discussed with regard to the table size for stationaryand moving UTs). Once the UT receives the response message from the GN,the UT may replace overlapping entries and append new entries to itscurrent table.

Option 2 enables the procedure to piggyback on Radio connections thatare established by the UT for various reasons, such as, when the UT hasuplink (UL) data to transmit, or when the UT responds to a page, or whena periodic timer (e.g., a 54 minute period) expires. Thus, no additionalconnections may need to be set up to send a request or receive an idlemode handoff table in these scenarios. In some implementations, thetimer could be a paging area update timer. Other types of timers couldbe used in other implementations.

Option 4 is a combination of Option 1 and Option 3. For example, the UTmay establish a Radio connection to obtain a new table whenever the UTapproaches the end of its current table. In addition, the UT may requesta table whenever a Radio connection is established for other reasons. Anexample of option 4 follows.

When an idle UT finds it has one entry left in its current table, the UTRadio triggers a control layer to initiate a Service Request procedureand establish a Radio connection to a GN. The UT then sends the handoffrequest over the connection, and the GN provides the UT a new table inresponse. The UT then replaces its current table with the new table.

As discussed above, stationary UTs and moving UTs may have differentconstraints. Stationary UTs may benefit from a large table (10 hours ormore) to reduce connection overhead. Moving UT may use a smaller tableas significant movement could invalidate the table. Thus, the amount ofhandoff information sent by the GN may be based on the movement (e.g.,speed) of a UT.

As discussed above, the UT may send the handoff table request messagewhenever a UT gets Radio connected to the GN. Upon receipt of thismessage, the GN determines whether the UT should be provided a table. Astationary UT need not be provided a new table if the UT's current tablehas entries for sufficient time into the future. For a moving UT, the GNcan provide tables of smaller size. The UT can append (e.g., replacingoverlapping entries) to its handoff table upon receiving the responsemessage.

Example Timeline

FIG. 9 shows an example timeline 900 at an idle UT as the idle UTswitches from a first satellite (designated SAT1) to a second satellite(designated SAT2) according to a handoff table. This example is for a UTwith dual, parabolic antennas. In an example implementation, the worstcase time 902 for the UT's antenna (e.g., an antenna 2) to completerotation and point towards SAT2 is indicated. In an example scenario,such an antenna may take about 5 seconds to rotate through an elevationrange of 90 degrees (e.g., the minimum elevation sweep speed at aparticular azimuth may be 18 degrees/second).

At time 904, the UT's antenna (the antenna 2) begins to rotate and pointtowards SAT2. At time 906, the UT reads the BIB in the current cell tofind the next cell to tune to. At a paging occasion (PO) 908, the UTuses another antenna (e.g., an antenna 1) to monitor a control channelin a subframe to determine whether there is a page for the UT 910. Atthe SAT2 start time 912, the UT's antenna 2 points towards the secondsatellite SAT2. At time 914, the UT measures FSL frequencies in the nextcell to camp on. For example, the UT may measure for 120 milliseconds orfor some other period of time. At time 916, the UT reads and processesBIB1. For example, the UT may perform these operations for 85milliseconds or for some other period of time. The UT attends to a pageduring the PO 918. In an example implementation, the page cycle 920 is1280 milliseconds.

Additional Handoff Operations

Referring to FIG. 10, various aspects of the disclosure relate tohandoff of a UT 1002 in communication with a GN 1004 via a satellite1006 in a satellite communication system 1000. In some implementations,the system 1000 may be a non-geosynchronous satellite communicationsystem, such as a low-earth orbit (LEO) satellite communication system,for data, voice, video, or other communication. The UT 1002 is anexample of the UT 400 or the UT 401 of FIG. 1. The GN 1004 is an exampleof the GN 200 or the GN 201 of FIG. 1. The satellite 1006 is an exampleof the satellite 300 of FIG. 1.

In some aspects, the GN 1004 and the UT 1002 use satellite and celltransition information 1008 to determine when to handoff the UT 1002from one cell to another and/or from one satellite to another. Forexample, the UT 1002 may send UT information 1010 (e.g., capabilityinformation, location information, or other information) to the GN 1004via first signaling 1012. Based on the information 1010, the GN 1004 orsome other entity generates the satellite and cell transitioninformation 1008 and sends the information 1008 to the UT 1002 viasecond signaling 1014. Alternatively, or in addition, the GN 1004 orsome other entity selects a handoff procedure for the UT 1002 based onthe information 1010. In some aspects, handoff of the UT 1002 to adifferent satellite (a new serving satellite) involves the UT 1002conducting satellite signal measurements and sending a measurementmessage 1016 to the GN 1004. In some aspects, the GN 1004 generates newsatellite and cell transition information (e.g., modifies a satelliteand cell transition table) as a result of receiving the measurementmessage 1016.

The UT 1002 may perform other handoff-related operations in accordancewith the teachings herein. In some aspects, the UT 1002 may receivesatellite ephemeris information via the GN 1004 and use the satelliteephemeris information to synchronize to a satellite (e.g., the satellite1006). In some aspects, the UT 1002 invokes a radio link failure mode ifthe UT 1002 loses connectivity to a satellite and/or cell.

In some aspects, a handoff design may attempt to meet one or more designobjectives. Example of such objective include: minimize signaling duringhandoffs; minimize data outage during handoffs; or reduce reliance onthe UT's knowledge of the satellite ephemeris data (e.g., insteadrelying on the GN's knowledge of the satellite location and the UTlocation).

In the example of FIG. 10, the GN 1004 includes network accesscontrollers (NACs) 1018, each of which interfaces with one or more radiofrequency (RF) subsystems 1020 for communicating with the UT 1002 andother UTs (not shown) via the satellite 1006 (or some other satellite,not shown). The GN 1004 also includes a core network control plane(CNCP) 1022 and a core network user plane (CNUP) 1024, or other similarfunctionality (e.g., control and user plane functionality for othertypes of networks), for communicating with a network 1026. The network1026 may represent, for example, one or more of a core network (e.g.,3G, 4G, 5G, etc.), an intranet, or the Internet.

In some implementations, the GN 1004 determines (e.g., receives orgenerates) the satellite and cell transition information 1008. Forexample, an NAC 1018 may generate satellite and cell transitioninformation for all UTs under the control of the NAC 1018 based oninformation (e.g., ephemeris information) received via the network 1026and information (e.g., configuration information and measurementmessages) received from UTs. As another example, an NAC 1018 may receivethe satellite and cell transition information for its UTs via thenetwork 1026 (e.g., from a network entity 1028).

Other entities in the system could generate the satellite and celltransition information 1008 as well. In some implementations, acontroller 1030 of the network entity 1028 may generate the satelliteand cell transition information 1008 and send the satellite and celltransition information 1008 to control components of the system 1000(e.g., during system startup and/or at other times). For example, thenetwork entity 1028 may transmit the satellite and cell transitioninformation 1008 to the GN 1004 via the network 1026 (e.g., a corenetwork, an intranet, or the Internet) or some other data transfermechanism. For purposes of illustration, the network entity 1028 isdepicted as being outside of the network 1026. However, the networkentity 1028 could be part of the network 1026.

Several example aspects of a UT, a GN, or a satellite that may be usedin conjunction with handoff of a UT in accordance with the teachingsherein will now be described. These aspects may include, for a given oneof these satellite system components, one or more of: a parameter orother information used by the component, a parameter assigned to thecomponent, a characteristic (e.g., capability) of the component,signaling used by the component, or an operation performed by thecomponent.

Satellite ID

A Satellite Identifier (ID) is a unique ID of a particular satellitewithin a satellite system. The Satellite ID allows the satellite to beuniquely identified within the satellite system (e.g., by a UT). Toallow for a large satellite deployment, A Satellite ID could be 16 bitsor more. In some implementations, the Satellite ID is transmitted on anoverhead channel and is not required to be read immediately by the UT.The UT and the GN may use a Satellite ID to index an ephemerisinformation table to locate the satellite and the projections of thesatellite's cells on the earth at a given time.

Cell or Beam ID

A Cell ID is a unique ID for a cell. Similarly, a Beam ID is a unique IDfor a beam. For convenience, the term cell/beam may be used herein toindicate a cell and/or a beam. The Cell/Beam ID allows a cell/beam froma given satellite to be uniquely identified (e.g., by a UT). In someaspects, a Cell/Beam ID may be detectable by a UT in a very short periodof time (e.g., the Cell/Beam ID may be a continuous signature used onthe pilot of the cell/beam). Thus, a UT might not need to decode anoverhead message to discover a Cell/Beam ID. In one non-limitingexample, a Cell/Beam ID could include 10 bits: 2 bits for a GN ID (e.g.,2 bits may be sufficient to have a unique GN visible by a UT; and the 4values for the GN ID could be reused across the globe); and 8 bits forthe cell/beam commanded by a GN (e.g., a GN controls approximately 10satellites×16 beams/satellite=160 beams/GN=>8 bits to uniquely identifythe cells/beams). A different number of bits could be used in otherimplementations. Also, spatial diversity of the satellites could betaken into consideration to reduce the number of bits.

UT Capabilities

A UT may exchange its capabilities with the GN at connection time orsome other time. Several non-limiting example of UT capabilities follow.

A UT may be dual cell/beam sense capable. Thus, one UT capabilityparameter (e.g., that takes a value of YES or NO) may indicate whetherthe UT is capable of sensing more than one cell/beam. For example, thiscapability parameter may indicate, while the UT is activelycommunicating using a cell/beam of a particular satellite, whether theUT can sense and detect a Cell/Beam ID of another cell/beam of the samesatellite. In some implementations, this capability parameter can beused to indicate whether a UT can support two cells/beams at the sametime. A different number of cells/beams (e.g., three or more) could besupported in other implementations.

A UT may be dual satellite sense capable. Thus, another UT capabilityparameter (e.g., that takes a value of YES or NO) may indicate whetherthe UT is capable of sensing more than one satellite. For example, thiscapability parameter may indicate, while the UT is activelycommunicating using a cell/beam of a particular satellite, whether theUT can sense and detect a Cell/Beam ID of another satellite. In someimplementations, this capability parameter can be used to indicatewhether a UT can support two satellites at the same time. A differentnumber of satellites (e.g., three or more) could be supported in otherimplementations.

As discussed in more detail below, a GN may use the sense capability ofa UT to determine what type of handoff to use for the UT. For example,if a UT can only support a single cell/beam at a time, handoff couldsimply be based on the satellite and cell transition table. Conversely,if a UT can support multiple cells/beams/satellites at a time, a GNcould monitor for a measurement message from a UT during handoff,whereby the measurement message may affect how (e.g., when and/or where)the UT is handed-off.

Another UT capability parameter may indicate the inter-cell tune timeand/or inter-beam tune time (e.g., in microseconds (psec)) for a UT. Forconvenience, the term inter-cell/beam tune time may be used to refer tothe inter-cell tune time and/or the inter-beam tune time. This UTcapability parameter may indicate the time duration it takes for the UTto stop listening to a cell/beam and start listening to anothercell/beam of the same satellite. Thus, in some aspects, theinter-cell/beam tune time indicates how long it takes a UT to tune fromone cell/beam to another cell/beam.

Another UT capability parameter may indicate the inter-satellite tunetime (e.g., in microseconds (μsec)) for a UT. This UT capabilityparameter may indicate the time duration it takes for the UT to stoplistening to a cell/beam on the current satellite and start listening toa cell/beam of another satellite. Thus, in some aspects, theinter-satellite tune time indicates how long it takes a UT to tune fromone satellite to another satellite.

In some implementations, a tune time may be given as an upper bound. Forexample, a tune time may indicate the maximum amount of time that the UTis expected to take to tune from one cell/beam or satellite to another.

In some implementations, a tune time may be described according to aformula. A non-limiting example of such a formula is: a+b*τ where, a isa constant that indicates the minimum time duration for theinter-satellite tuning, τ is the angular distance (in degrees) betweenthe current satellite and the target satellite, and b is the movementspeed of the UT's antenna in degrees of movement per millisecond.

Tune-Away Definitions

Signaling may be employed to allow a UT to tune-away for inter-satelliteand inter-cell/beam sensing. This signaling can be used to definetune-away periods for a UT to sense other cells/beams of the samesatellite or other satellites.

UT Location

A UT location reporting mechanism is employed for handoff processing andpaging so that the GN will know the location of the UT (e.g., on acontinual or regular basis). In some implementations, a UT will havereliable global positioning system (GPS) positioning.

For stationary UTs, the UT location reporting mechanism may involve theUT sending a signaling message to the GN that reports the location(e.g., the GPS coordinates) of the UT.

For mobile UTs (e.g., UTs on a ship or an airplane), the UT locationreporting mechanism may involve the UT sending a signaling message tothe GN that reports the speed and direction of the UT. This allows theGN to continuously estimate the location of the UT. Even for mobile UTs,the direction and speed information may be relatively stable if the UTsare carried by (e.g., attached to) relatively large vessels.

Also, via location-related signaling, the UT may be informed of thelocation drift allowed before a new location update message is needed.

Some implementations may employ thresholds for location tolerance. Someimplementations may employ GEO fencing. For example, if a UT is beyond adesignated boundary relative to a satellite and/or a GN (e.g., the UT isa certain distance away), the UT may be configured to send a locationupdate to the GN.

Ephemeris Transfer and Update Signaling

Ephemeris Transfer and Update signaling messages may be used to transfersatellite ephemeris data to the UTs. In some aspects, ephemeris dataincludes a geographic description of where a given satellite is at agiven point in time. This data may be used by the UT when it searchesfor the next satellite and cell/beam (e.g., after the UT detects a radiolink failure). For example, in some aspects, a UT may use the ephemerisdata for a given satellite to determine where to point the UT's antenna(antennas) at a given point in time. In some aspects, a GN may transmita signaling message containing the satellite ephemeris data to allconnected UTs (e.g., whenever there is an update). In some aspects, a UTmay request satellite ephemeris data from the GN (e.g., when the UTestablishes a connection).

Satellite and Cell Transition Tables

Each satellite beam may be regarded as a separate cell with its own dataand control channels, and signals. The GN or some other entity maygenerate a satellite and cell transition table that provides a list ofsatellites to which a UT may choose to handoff next. The transitiontable also may dictate exactly at what time the UT will switch over fromone cell (e.g., corresponding to a beam and/or an RF band) of the nextsatellite to another. A transition table may indicate, for a number ofsatellites, the cells (e.g., the beams and/or the bands) to be used foreach satellite. A transition table may indicate, for each cell (e.g.,beam), the frequency (e.g., the nominal radio frequency or frequencyband) of the cell. A transition table may also indicate the Cell ID ofeach Cell (or Beam ID of each beam).

A GN may define a satellite and cell transition table based on variousinformation. In some aspects, a GN may define the table using thelocation (and speed and direction, if specified) of the UT. In someaspects, a GN may define the table using satellite locations over timecalculated from ephemeris data. In some aspects, a GN may define thetable based on information regarding whether certain cells/beams and/orsatellites are turned off at certain times.

Table 2 below is one example of a satellite and cell transition table.The entries for this table include Satellite IDs, Beam IDs, BeamFrequencies (Freq), Start Times, and End Time. This table could also bereferred to as a satellite and beam transition table. TAbeam denotes thetune-away time from one beam to another of the same satellite. In thisexample, the UT is to tune to Satellite 1, Beam 1 (on frequency F11)from time a1 to time b1. The UT is to then tune to Satellite 1, Beam 2(on frequency F21) from time b1+TAbeam to time c1, and so on.

In some implementations, the table may be sent in a signaling message bythe GN to the UT it is serving, at any time before the UT is handed-offto the next satellite.

TABLE 2 Start Time End Time Satellite Beam (e.g., Frame (e.g., Frame IDID Freq. Number) Number) Satellite 1 Beam 1 F₁₁ a₁ b₁ Beam 2 F₂₁ b₁ +TA_(beam) c₁ . . . . . . . . . . . . Beam N F_(N1) m₁ + TA_(beam) n₁Satellite 2 Beam 1 F₁₂ a₂ b₂ Beam 2 F₂₂ b₂ + TA_(beam) c₂ . . . . . . .. . . . . Beam N F_(N2) m₂ + TA_(beam) n₂ . . . . . . . . . . . . . . .

In one example, the overhead of the satellite and cell transition tablemessage is as follows (assuming that there are two satellites listed inthe table): Satellite ID=16 bits; Beam ID=10 bits; Freq.=4 bits(assuming 16 beam frequencies per satellite); and Start and End Times=15bits.

The Start Time and the End Time can be specified in terms of FrameNumbers. The physical layer may specify the use of 10 millisecond (ms)transmission frames for the system. Assuming that a satellite handofftakes place every 3 minutes, the number of frames that can betransmitted between handoffs is 18,000. Frame Numbers can bere-initialized from zero after every handoff. The number of bits thatare then required to specify the Frame Numbers is thus 15 bits in thisexample.

In the above example, the total overhead of the message would be 1020bits=128 bytes (approximately). The values of a1, b1, . . . , n1, TAbeamwould be specified.

If a maximum of 1000 active users can be served at any time by one beam,and if a beam overall downlink (DL) throughput is approximately 300Mbps, the overhead is given by: overhead=(128 bytes×numUsersBeam)/(totalbytes delivered by beam over 3 minutes)=(128bytes×1000)/(300×106×3×60)=19×10−6 (approximately).

Table 3 below is another example of a satellite and cell transitiontable. SatelliteID is a unique ID assigned to a satellite in the system.The forward link (FL) Band is a positive integer index that identifies atransmission frequency band of the FL. The return link (RL) Band is apositive integer index that identifies a transmission frequency band ofthe RL.

Handoff Activation Time specifies the time when a UT should stoptransmitting and receiving. In some implementations, this time isspecified in the source cell in units of System Frame Numbers (SFNs).SFNs may be, for example, sequence numbers assigned to 10 ms physicallayer transmission radio frames. The UT stops transmitting and receivingat the beginning of the SFN. For example, if the Handoff Activation Timeis specified to be at the SFN 5, then the UT stops transmitting orreceiving at sub-frame 0 of the SFN 5.

TABLE 3 FL RL RL Handoff Activation SatelliteID Band Band . . . BandTime (e.g., SFN) Satellite 1 F₁ R₁₁ . . . R_(1M) a₁ F₂ R₂₁ . . . R_(2M)a₂ . . . . . . . . . . . . . . . F₁₆ R_(16,1) . . . R_(16,M) a₁₆Satellite 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . .

The UT starts transmitting or receiving in the target cell at theHandoff Activation Time plus a tune-away time. Two examples of UTparameters related to the tune-away time are an inter-cell tune-awaytime and an inter-satellite tune-away time. These parameters may beincluded in the UT Capability information.

Inter-Satellite Handoff

FIGS. 11 and 12 illustrate examples of inter-satellite handoff. In theseexamples, the GN includes a source NAC that controls a first satelliteand a target NAC that controls a second satellite. In each case, the UTinitially is connected to a source satellite (and, hence, the sourceNAC) and is subsequently handed-off to a target satellite (and, hence,the target NAC). A different number of NACs and satellites could besupported in other implementations. Also, in some implementations, acommon (e.g., the same) entity could support multiple satellites.

FIG. 11 is an example where a UT 1102 does not send a measurementmessage. For example, the UT 1102 might not support the sensing ofmultiple cell/beams and/or satellites or the UT 1102 may determine thata measurement message need not be sent to a GN 1104. In this case, theUT 1102 and the GN 1104 rely on the existing satellite and celltransition table to determine when to transition to the next cell/beamand/or satellite and where to transition (e.g., which cell/beam, whichfrequency, which satellite). The UT 1102 is an example of the UT 400 orthe UT 401 of FIG. 1. The GN 1104 is an example of the GN 200 or the GN201 of FIG. 1.

A source NAC 1106 sends control signaling 1108 to the UT 1102. Thiscontrol signaling 1108 may include, for example, measurement informationand tune-away control information (e.g., tune-away definitions). Inaddition, packet data 1110 is exchanged between the UT 1102 and thesource NAC 1106. The source NAC 1106 is an example of the NAC 1012 ofFIG. 10.

At some point in time a handoff is triggered 1112. For example, thecurrent time may correspond to the time for a transition from onesatellite to the next indicated by the satellite and cell transitiontable.

Other handoff triggers may be employed as well. For example, the GN 1104(e.g., the source NAC 1106) may decide autonomously that the UT 1102needs to be handed-off. Such a trigger may be due to, for example: thecurrent serving satellite is moving out of range of the UT 1102; thesatellite is moving out of the range of the GN 1104, even if it may bewithin the range of the UT 1102; or the cell/beam serving the UT 1102will be blacked-out due to GEO requirements.

In the event the UT 1102 is capable of sensing another cell/beam and/orsatellite while connected to the first satellite, the UT 1102 may searchthe signal strength of the default satellite and cell/beam for handoff.It may be assumed that the UT 1102 has the location information of thissatellite in order to do so. This location information can be obtainedfrom the satellite ephemeris data the UT 1102 possesses. If the signalstrength is satisfactory, the UT 1102 does nothing and waits for thesource NAC 1106 to start the inter-satellite handoff process.

Thus, in the example of FIG. 11, both the UT 1102 and the source NAC1106 will follow the table and commence the handoff to a new servingsatellite. To this end, the source NAC 1106 will perform handoffprocessing 1114. For example, the source NAC 1106 may communicate with atarget NAC 1116 to commence the handoff. In some aspects, this mayinvolve synchronizing the queues 1118 (e.g., packet traffic queues)between the NACs 1106 and 1116. Also, as the time of the handoff isknown ahead of time, the user queues can be transferred ahead of time.The target NAC 1116 is an example of the NAC 1012 of FIG. 10.

The source NAC 1106 then sends handoff signaling 1120 to the UT 1102. Insome aspects, this handoff signaling 1120 may include information thatenables the UT 1102 to communicate with the target NAC 1116. In someaspects, this handoff signaling 1120 may include a new satellite andcell transition table (e.g., that the source NAC 1106 received from thetarget NAC 1116).

The UT 1102 then detaches 1122 from the first satellite and synchronizesto the second satellite. To this end, the UT 1102 may sendsynchronization signaling 1124 for the second satellite to the targetNAC 1116. In some aspects, this may involve the UT 1102 performing arandom access procedure at the second satellite.

The UT 1102 and the target NAC 1116 may then exchange connectionsignaling 1126 and 1128. In some aspects, this may involve the targetNAC 1116 sending ephemeris information to the UT 1102 and requesting achannel quality indicator from the UT 1102. In some aspects, the UT 1102may use the ephemeris information to synchronize with the secondsatellite.

Also, the various entities may perform various background operations toensure that packet forwarding is done properly and any needed clean-up(e.g., cache clean-up) is performed.

FIG. 12 is an example where a UT 1202 does send a measurement message.For example, the UT 1202 might determine that a measurement messageneeds to be sent to a GN 1204 because the measured channel conditions(e.g., signal strength) from the serving satellite or the targetsatellite are unacceptable (e.g., the signal strength is too low). Inthis case, the GN 1204 may generate a new satellite and cell transitiontable based on the measurement message. The UT 1202 and the GN 1204 willthen use the new satellite and cell transition table to determine whento transition to the next cell/beam and/or satellite and where totransition (e.g., which cell/beam, which frequency, which satellite).The UT 1202 is an example of the UT 400 or the UT 401 of FIG. 1. The GN1204 is an example of the GN 200 or the GN 201 of FIG. 1.

As in FIG. 11, a source NAC 1206 sends control signaling 1208 to the UT1202. This control signaling 1208 may include, for example, measurementinformation and tune-away control information (e.g., tune-awaydefinitions). In addition, packet data 1210 is exchanged between the UT1202 and the source NAC 1206. The source NAC 1206 is an example of theNAC 1012 of FIG. 10.

At some point in time a handoff is triggered 1212. In some cases, thecurrent time corresponding to the time for a transition from onesatellite to the next as indicated by the satellite and cell transitiontable constitutes a handoff trigger. In some cases, a measurementmessage sent by the UT 1202 indicating that a neighbor satellite ismaterially stronger (e.g., associated with a stronger received signalstrength) than a current serving satellite may constitute a handofftrigger.

Other handoff triggers may be employed as well. For example, the GN 1204(e.g., the source NAC 1206) may decide autonomously that the UT 1202needs to be handed-off. Such a trigger may be due to, for example: thecurrent serving satellite is moving out of range of the UT 1202; thesatellite is moving out of the range of the GN 1204, even if it may bewithin the range of the UT 1202; or the cell/beam serving the UT 1202will be blacked-out due to GEO requirements.

In the example of FIG. 12, the UT 1202 is capable of sensing anothercell/beam and/or satellite while connected to the first satellite. Thus,the UT 1202 may perform channel quality measurements (e.g., satellitesignal strength measurements). For example, the UT 1202 may measure 1214the signal strength from the current serving satellite (first satellite)and the target satellite (second satellite).

The UT 1202 then performs measurement processing 1216 to determine, forexample, whether either channel quality is inadequate (e.g., signalstrength is too low). In the event either channel quality is inadequate,the UT 1202 may elect to send a measurement message 1218 to the sourceNAC 1206. This measurement message 1218 may include, for example, theresults of the measurements (e.g., signal strength in dB), an indicationthat the handoff time needs to be advanced (e.g., because the signalfrom the source satellite is currently too low), an indication that thehandoff time needs to be delayed (e.g., because the signal from thetarget satellite is currently too low), or some other indication.

Thus, similar to FIG. 11, the UT 1202 may search the signal strength ofthe default satellite and cell/beam for handoff. Again, it may beassumed that the UT 1202 has the location information of this satellitein order to do so (e.g., obtained from the satellite ephemeris data theUT 1202 possesses). If the signal strength is not satisfactory, the UT1202 may send a measurement message 1218 to the source NAC 1206indicating a satellite different from the default one, to trigger thehandoff process early or delay it.

The source NAC 1206 may thus make a decision to handoff the UT 1202 to atarget satellite and a target NAC 1220 based on the satellite and celltransition table and on any measurement message 1218 the source NAC 1206receives from the UT 1202. Thus, as indicated in FIG. 12, the source NAC1206 will perform some handoff processing 1222. For example, the sourceNAC 1206 may decide, based on the measurement message 1218, whether thehandoff time needs to be advanced (early handoff) or delayed (latehandoff), or whether some other satellite should be selected as thetarget. In addition, the source NAC 1206 may communicate with a targetNAC 1220 to commence the handoff. In some aspects, this may involvesynchronizing the queues 1224 (e.g., packet traffic queues) between theNACs 1206 and 1220. The target NAC 1220 is an example of the NAC 1012 ofFIG. 10.

The source NAC 1206 then sends handoff signaling 1226 to the UT 1202. Insome aspects, this handoff signaling 1226 may include information thatenables the UT 1202 to communicate with the target NAC 1220. In someaspects, this handoff signaling 1226 may include a new satellite andcell transition table (e.g., that the source NAC 1206 received from thetarget NAC 1220).

The UT 1202 then detaches 1228 from the first satellite and synchronizesto the second satellite. To this end, the UT 1202 may sendsynchronization signaling 1230 for the second satellite to the targetNAC 1220.

The UT 1202 and the target NAC 1220 may then exchange connectionsignaling 1232 and 1234. In some aspects, this may involve the targetNAC 1220 sending ephemeris information to the UT 1202 and requesting achannel quality indicator from the UT 1202. Again, the various entitiesmay perform various background operations to ensure that packetforwarding is done properly and any needed clean-up (e.g., cacheclean-up) is performed.

With normal inter-satellite handoff, hybrid automatic repeat request(HARQ) processes may be terminated. However, the source NAC may knowexactly when the handoff will happen, therefore the source NAC canensure that the forward link data buffers are drained. Also, the gap fordata flow can be minimized since the time of handoff is known.

Inter-Beam Handoff

Inter-cell/beam handoff is executed by the GN and the UT synchronouslyaccording to the timeline specified in the satellite and cell transitiontable. Using the tune-away periods or dual receive capability, the UTdetects the presence of the next cell/beam specified in the satelliteand cell transition table. If the UT detects the next cell/beamsuccessfully, a normal inter-cell/beam handoff is executed without anysignaling between the UT and the GN.

With normal inter-cell/beam handoff, forward link HARQ processes may becarried over from one cell/beam to the next. In addition, reverseassignments may be cancelled as the UT hands-off from one cell/beam tothe next. For example, the UT may instead send new request messages tosend reverse link data.

Exception Scenarios

If the UT loses the current serving cell/beam before the expiration ofthe specified time in the satellite and cell transition table, the UTenters into radio link failure (RLF) mode. In RLF mode, the UT mayattempt to find an alternate cell/beam or satellite (e.g., based on theephemeris information at the UT). For example, the UT may attempt toconnect to the next satellite that should be serving the UT. If the UTsuccessfully establishes another connection, the UT can send signalingmessages to the GN to continue communication where the UT left offbefore the RLF.

While being served by a cell/beam, the UT may fail to detect the nextcell/beam specified in the satellite and cell transition table, but maydetect another cell/beam. This may happen, for example, to a fast movingUT (e.g., a UT attached to an airplane). In this case, the UT may send ameasurement message to initiate another handoff procedure. In addition,the UT may also send a position update if it has moved since the lasttime a position update was sent. In response, the GN may send an updatedsatellite and cell transition table. In this case, the UT follows theupdated table. Alternatively, the GN may start a completely new handoffprocess.

Example Connected Mode Handoff Details

Referring now to FIGS. 13-23, various aspects of radio connected modehandoff in accordance with the teachings herein will be described inmore detail. The following describes examples of call flows for variousconnected mode handoff operations. In addition, the following detailsdescribe several procedures that may be used to improve handoffperformance. In various aspects, these procedures may be used to definehandoff measurements, determine when to trigger the measurements,determine when to handoff a UT, or determine whether to trigger a UT toobtain return link synchronization after a handoff. For purposes ofexplanation, these details will be discussed in the context of a NACthat comprises two components, a B×P and an A×P, for controlling and/orcommunicating with a satellite.

FIG. 13 illustrates an example deployment of B×P and A×P components in asatellite system. At a given point in time, a UT 1306 communicates withone of the A×Ps 1308 via a satellite 1310 and one of the B×Ps 1312,where each B×P 1312 includes or is associated with a satellite RFsubsystem 1314.

A B×P refers to a combination of a BCP and a BTP (hence, the acronymB×P). In some aspects, a B×P may include radio network components forcontrolling a satellite. For example, a B×P may include, for a givencell/beam of a satellite, a corresponding set of digital circuits thatserves that cell/beam. Thus, in some aspects, a B×P corresponds to aparticular antenna. Also, in some aspects, a given B×P may be associatedwith a particular band for a given cell/beam of a satellite.

An A×P refers to a combination of an ACP and an ATP (hence, the acronymA×P). In some aspects, an A×P corresponds to an anchor point. In someaspects, an anchor point may be associated with a particular region(e.g., an administrative region, a country boundary, etc.). A given A×Pmay serve one or more satellites. Also, a given satellite may serviceone or more A×Ps.

In the above scenario, a UT in connected mode may undergo two types ofhandoff: B×P handoff or A×P handoff. For example, as satellites move ina non-GSO satellite system, the cells/beams (and, hence, the circuitsand antennas associated with those cells/beams) used to serve a given UTwill change over time. Thus, in some aspects, a B×P handoff maycorrespond to a handoff to a different cell/beam (or antenna, etc.). Asanother example, rain fade on a particular cell/beam operating on afirst band may necessitate a switch to a different band for thatcell/beam. Thus, in some aspects, a B×P handoff may correspond to ahandoff to a different band for a given cell/beam. An A×P handoffcorresponds to handoff to a different anchor point. For example, a UTmay move to a different administrative region, thereby necessitating achange in the serving A×P. A B×P handoff might or might not beassociated with an A×P handoff.

In some aspects, the disclosure that follows addresses satellitepointing errors that may occur in a satellite communication system.These errors may result from various causes in the system.

The graph 1400 of FIG. 14 illustrates expected gain contours 1402 and1404 from different satellite beams, a first expected beam and a secondexpected beam, respectively. In some aspects, these beam gain contoursmay be used to determine when to handoff a UT from one beam to the next.For example, a UT may be handed over when the beam gain from the firstexpected beam (a source beam) that is currently serving the UT dropsbelow the beam gain of the second expected beam (a candidate targetbeam).

For the first expected beam, FIG. 14 illustrates an actual beam gaincontour 1406 that may be seen by a UT due to a satellite pointing error.As indicated in FIG. 14, a shift 1408 in the gain contour due to asatellite pointing error shifts the gain contour intersection betweenthe two beam contours from a first intersection 1410 to a secondintersection 1412. Thus, at the expected (ideal) handoff time 1414, thegain from the first beam will be lower (by the indicated amount) thanthe expected gain 1416, thereby adversely affecting handoff performance.As a result, the signal quality at the UT may be lower than desiredimmediately prior to handoff. To address this issue, the ideal handofftime may be shifted by a Δ (earlier in time in this example) based onthe shift 1408 in the beam contour due to the satellite pointing error.Thus, handoff will occur at a new handoff time 1418. As shown in FIG.14, the gain 1420 at the new handoff time 1418 may be lower by a Δ gain1422 than the expected gain 1416 associated with the expected firstbeam.

To this end, a UT may conduct measurements of satellite signals (e.g.,inter-satellite and intra-satellite) and send this information to a GN.Based on these signals, the GN may modify the handoff time for the UT.Accordingly, a GN may send updated handoff information to a UT (e.g.,via a satellite and cell transition table or a subset of the satelliteand cell transition table) to account for the satellite pointing error.

In some aspects, a random access procedure may be used in scenarioswhere a UT has not yet achieved synchronization with a satellite duringa handoff. For example, a random access procedure based on UTmeasurements of satellite signals may allow a UT to achieve return linksynchronization.

B×P Handoff

A logical B×P may be uniquely identified by a 4-tuple including asatellite access network (SAN), a GN antenna, a Satellite Beam, and aforward service link (FSL) Frequency, where GN Antenna refers to theantenna in FIG. 13. A B×P handoff occurs for a UT in radio connectedmode if the B×P 4-tuple of its connection changes.

Table 4 lists an example of these four types of B×P handoffs and thechanges (highlighted in bold) associated with the B×P 4-tuple for eachtype of B×P handoff. For the Feeder Link Switching handoff, only the B×Pchanges, not the entire SAN.

TABLE 4 Type of BxP handoff BxP-4 tuple changes (in bold) Intra-Sathandoff (SAN, GN Antenna, Sat Beam, FSL Frequency) Inter-Sat handoff(SAN, GN Antenna, Sat Beam, FSL Frequency) Feeder Link (SAN, GN Antenna,Sat Beam, FSL Frequency) Switching handoff Intra-GN, GN (SAN, GNAntenna, Sat Beam, FSL Frequency) antenna failover

The B×P handoff occurs at either a handoff time based upon a prioriinformation, denoted as THO_a_priori, or a new handoff time recalculatedusing UT measurement reports, denoted as THO_recalc, whereTHO_recalc=THO_a_priori (e.g., as in FIG. 14).

If the satellite antenna pointing errors are well known a priori, thenthe B×P handoff shall be initiated by the UT based solely upon itsSatellite Handoff Table (e.g., satellite and cell transition table).Otherwise, the B×P handoff may require UT measurements of the targetcell and subsequent measurement reporting by the UT to the source A×Pbased upon which the source A×P shall update the UTs satellite and celltransition table.

B×P Handoff—Feeder Link Switching

Referring again to FIG. 13, a first configuration 1302 and a secondconfiguration 1304 illustrate a feeder link switching B×P handoff. Eachsatellite has dual feeder link connections to two GNs, but only onefeeder link connection is active at any one time. The dual feeder linkconnections allow instantaneous switching of the active feeder linkconnection at a satellite. The feeder link switching appears as anidempotent handoff in which the UT hands over to the same satellite, thesame cell and the same frequency. However, the feeder link switching B×Phandoff can also be made to occur at the same time as a cell handoff forsome UTs, in which case the target cell is different from the sourcecell.

The call flows for feeder link switching B×P handoff are the same asthose illustrated in FIG. 15 and FIG. 17 discussed below. The call flowin FIG. 15 is applicable for the case where the UT does not need toperform a Random Access procedure in order to achieve RL synchronizationafter the feeder link switching occurs. The call flow in FIG. 17 isapplicable for the case where the UT does need to perform a RandomAccess procedure in order to achieve RL synchronization after the feederlink switching occurs.

B×P Handoff—Non-Random Access

FIG. 15 illustrates a non-Random Access-based B×P handoff call flowwithout UT measurements and measurement reporting. A typical use-case isan intra-satellite B×P handoff. The call flow is between a UT 1502, asource B×P 1504, a target B×P 1506, a source A×P 1508, and a GN 1510.

A description of the steps in the non-Random Access-based B×P handoffcall flow without UT measurements and measurement reporting is providedbelow. Initial packet data flow is represented by lines 1512, 1514, and1516.

At point 1518, the source A×P 1508 pre-configures the target B×P 1506for handoff before (e.g., 1 second before) the handoff activation time(e.g., before THO_a_priori). At step 1A, the source A×P 1508 sends aRadio Connection Reconfiguration message to the UT 1502. At step 1B, themessage is sent to the UT 1502 sufficiently in advance of the handoffactivation time so that the UT 1502 has adequate time to receive themessage. This message may include satellite handoff information such asa row of a transition table (e.g., indicative of a handoff activationtime) and other parameters. The UT 1502 starts timer T-4. If T-4 expires(e.g., a handoff failure occurs), then the UT 1502 performs the RadioConnection Re-establishment procedure.

At steps 2A and 2B, based upon the single row of the satellite and celltransition table contained in the Radio Connection Reconfigurationmessage in step 1, both the UT 1502 and source A×P 1508 simultaneouslyprepare for B×P handoff at the handoff activation time (e.g., atTHO_a_priori). Thus, the UT 1502 prepares to handoff from the source B×P1504 to the target B×P 1506, and the source A×P 1508 prepares to handoffthe UT 1502 from the source B×P 1504 to the target B×P 1506.

At step 3, the UT 1502 resets the media access control (MAC) state. TheUT 1502 then acquires the new cell (e.g., FL synchronization).

At step 4, after the handoff activation+Inter-Cell Tune-away time, thetarget B×P 1506 sends to the UT 1502 an RL grant+channel qualityindicator (CQI) request. The RL grant is addressed to the UT identifier(UT-ID) that the source A×P 1508 assigned to the UT 1502 in the RadioConnection Reconfiguration message (see Step 1).

At step 5, upon receiving the RL grant from the target B×P 1506, the UT1502 stops timer T-4 (e.g., the handoff is successful) and sends a CQIreport and Radio Connection Reconfiguration Complete message to thetarget B×P 1506 (step 5A) for forwarding to the source A×P 1508 (step5B). The Radio Connection Reconfiguration Complete message contains noinformation elements (IEs) and is integrity protected and encrypted withthe old keys (e.g., Kint and Kenc, respectively). Final packet data flowis represented by lines 1520, 1522, and 1524.

FIG. 16 illustrates a non-Random Access-based B×P handoff call flow withUT measurements and measurement reporting. A typical use-case is anintra-satellite B×P handoff. The call flow is between a UT 1602, asource B×P 1604, a target B×P 1606, a source A×P 1608, and a GN 1610.

A description of the steps in the non-Random Access-based B×P handoffcall flow with UT measurements and measurement reporting follows.Initial packet data flow is represented by lines 1612, 1614, and 1616.

A Radio Connection Reconfiguration message sent to the UT 1602 while theUT 1602 is served by a given source cell may instruct the UT 1602 whento conduct measurements for the next target cell. Thus, at point 1617,while in the previous cell, the source A×P 1608 may configure the UT1602 with measurement gap information (e.g., a gap pattern)corresponding to a measurement time. The source A×P 1608 may send thisinformation because satellite pointing error may require satellitehandoff to occur at the ideal handoff time +/−Δ, thereby necessitatingmeasurements by the UT 1602. At steps 1A and 1B, the source A×P 1608sends a Radio Connection Reconfiguration message to the UT 1602. Themessage includes measurement gap configuration information andmeasurement activation/deactivation time (in addition to handoffactivation time and other IEs described herein). At step 3, the UT 1602measures the signal strength of the target cell according to themeasurement gap configuration information that it received from thesource A×P 1608. Packet data flow continues as represented by lines1618, 1620, and 1622.

At steps 4A and 4B, the UT 1602 sends a Measurement Report to the sourceA×P 1608 indicating the signal strength (e.g., RSRP) of both the sourcecell and target cell using event-based reporting of the signal strength.The source A×P 1608 configures the UT 1602 to use an Event 1 (sourcecell becomes better than a threshold) as the criteria to trigger ameasurement report. The source A×P 1608 sets the threshold low enough sothat the signal strength of the source cell is always greater than thethreshold, thereby triggering the UT 1602 to send a measurement reportto the source A×P 1608. Similarly, the source A×P 1608 configures the UT1602 to use an Event 4 (target cell becomes better than a threshold) asthe criteria to trigger a measurement report. The source A×P 1608 setsthe threshold low enough so that the signal strength of the target cellis always greater than the threshold, thereby triggering the UT 1602 tosend a measurement report to the source A×P 1608. Other reportingcriteria can also be used.

At step 5, based upon the UT measurement report (see Step 4), the sourceA×P 1608 calculates a new handoff activation time (e.g., THO_recalc) andpre-configures the target B×P 1606 for handoff before the new handoffactivation time (e.g., before THO_recalc). For example, based onsatellite ephemeris information, beam patterns, and the UT measurementreport, the source A×P 1608 may prepare for B×P handoff to occur at theideal handoff time +/−Δ. At steps 6A and 6B, the source A×P 1608 sends aRadio Connection Reconfiguration message to the UT 1602. The contents ofthe message are described herein, including the new handoff activationtime. Optionally, the message may also contain measurement gapconfiguration information and measurement activation/deactivation time.The message is sent to the UT 1602 sufficiently in advance of the newhandoff activation time so that the UT 1602 has adequate time to receivethe message. The UT 1602 starts timer T-4. If T-4 expires (e.g., ahandoff failure occurs), then the UT 1602 performs the Radio ConnectionRe-establishment procedure. Also, if the source A×P 1608 does notreceive the measurement report from the UT 1602 in a timely manner, thenthe source A×P 1608 uses the old handoff activation time (e.g.,THO_a_priori) when configuring both the target B×P 1606 and the UT 1602for handoff.

Based upon the single row of the satellite and cell transition tablecontained in the Radio Connection Reconfiguration message in Step 6,both the UT 1602 and source A×P 1608 simultaneously prepare for B×Phandoff at the new handoff activation time (e.g., THO_recalc).

At step 7, the UT 1602 resets the MAC state. The UT 1602 acquires thenew cell (e.g., FL synchronization).

At step 8A, after the handoff activation+Inter-Cell Tune-away time, thetarget B×P 1606 sends to the UT 1602 an RL grant+CQI request. The RLgrant is addressed to the UT-ID that the source A×P 1608 assigned to theUT 1602 in the Radio Connection Reconfiguration message (see Step 3).

Upon receiving the RL grant from the target B×P 1606, the UT 1602 stopstimer T-4 (e.g., the handoff is successful) and sends a CQI report (step8A) and Radio Connection Reconfiguration Complete message to the targetB×P 1606/source A×P 1608 (steps 9A and 9B). The Radio ConnectionReconfiguration Complete message contains no IEs and is integrityprotected and encrypted with the old keys (e.g., Kint and Kenc,respectively). Final packet data flow is represented by lines 1624,1626, and 1628.

B×P Handoff—Random Access

FIG. 17 illustrates a Random Access-based B×P handoff call flow withoutUT measurements and measurement reporting. A typical use-case is aninter-satellite B×P handoff. The call flow is between a UT 1702, asource B×P 1704, a target B×P 1706, a source A×P 1708, and a GN 1710.

A description of the steps in the Random Access-based B×P handoff callflow without UT measurements and measurement reporting follows. Initialpacket data flow is represented by lines 1712, 1714, and 1716.

At steps 1A and 1B, the source A×P 1708 pre-configures the target B×P1706 for handoff before the handoff activation time (e.g., beforeTHO_a_priori). The source A×P 1708 sends a Radio ConnectionReconfiguration message to the UT 1702. The contents of the message aredescribed herein. The message is sent to the UT 1702 sufficiently inadvance of the handoff activation time so that the UT 1702 has adequatetime to receive the message. The UT 1702 starts timer T-4. If T-4expires (e.g., a handoff failure occurs), then the UT 1702 performs theRadio Connection Re-establishment procedure.

At step 2, based upon the single row of the satellite and celltransition table contained in the Radio Connection Reconfigurationmessage in Step 1, both the UT 1702 and the source A×P 1708simultaneously prepare for B×P handoff at the handoff activation time(e.g., at THO_a_priori). These operations may be similar to thecorresponding operations discussed above in conjunction with FIG. 15.

At step 3, the UT 1702 resets the MAC state. The UT 1702 acquires thenew cell (e.g., FL synchronization). As represented by bracket 1718, ifstep 1 does not include an RA procedure order, steps 4-7 are notrequired.

After the handoff activation+Inter-Satellite Tune-away time, the targetB×P 1706 sends a FL control channel (FLCC) order to the UT 1702containing a dedicated preamble signature in order to trigger the UT1702 to perform a non-contention based Random Access procedure. Thisenables the UT 1702 to subsequently achieve RL synchronization.

At step 4, the UT 1702 sends a non-contention based Random AccessPreamble on the Random Access to the target B×P 1706. Upon receiving thenon-contention based Random Access Preamble from the UT 1702, the targetB×P 1706 validates the received signature sequence.

At step 5, the target B×P 1706 sends a Random Access Response to the UT1702 that is addressed to the appropriate group of UTs (e.g., RA-RNTI).The Random Access Response contains the paging area (PA), RL grant(which includes a CQI request), and temporary UT-ID.

If a dedicated preamble signature is used, the RL grant may include aCQI request. In this case, the process may skip from point 1720 to step8B. Otherwise, the operations of block 1722, including steps 6 and 7,and the operations of step 8A may be performed.

Upon receiving the RL grant+CQI request from the target B×P 1706 (e.g.,in step 8A), the UT 1702 stops timer T-4 (e.g., the handoff issuccessful) and sends a CQI report (step 8B) to the target B×P 1706. Ifa dedicated preamble signature is used, the UT 1702 also sends a RadioConnection Reconfiguration Complete message to the target B×P 1706 (step9A) for forwarding to the source A×P 1708 (step 9B). The RadioConnection Reconfiguration Complete message contains no IEs and isintegrity protected and encrypted with the old keys (e.g., Kint andKenc, respectively). Final packet data flow is represented by lines1724, 1726, and 1728.

FIGS. 18 and 19 illustrate a random access-based B×P handoff call flowwith UT measurements and measurement reporting. A typical use-case is aninter-satellite B×P handoff. The call flow is between a UT 1802, asource B×P 1804, a target B×P 1806, a source A×P 1808, and a GN 1810.

A description of the steps in the Random Access-based B×P handoff withUT measurements and measurement reporting follows. Initial packet dataflow is represented by lines 1812, 1814, and 1816.

Referring initially to FIG. 18, while in the previous cell, the UT 1802was configured by the source A×P 1808 in a Radio ConnectionReconfiguration message with measurement gap configuration informationand measurement activation/deactivation time (in addition to handoffactivation time and other IEs described herein). At step 1, the UT 1802measures the signal strength of the target cell according to themeasurement gap configuration information that it received from thesource A×P 1808. Packet data flow continues as represented by lines1818, 1820, and 1822.

At step 2, the UT 1802 sends a Measurement Report to the source A×P 1808indicating that the signal strength (e.g., RSRP) of both the source celland target cell using event-based reporting of the signal strength. Thesource A×P 1808 configures the UT 1802 to use an Event 1 (source cellbecomes better than a threshold) as the criteria to trigger ameasurement report. The source A×P 1808 sets the threshold low enough sothat the signal strength of the source cell is always greater than thethreshold, thereby trigger the UT 1802 to send a measurement report tothe source A×P 1808. Similarly, the source A×P 1808 configures the UT1802 to use an Event 4 (target cell becomes better than a threshold) asthe criteria to trigger a measurement report. The source A×P 1808 setsthe threshold low enough so that the signal strength of the target cellis always greater than the threshold, thereby triggering the UT 1802 tosend a measurement report to the source A×P 1808. Other reportingcriteria can also be used.

Based upon the UT measurement report (see Step 2), the source A×P 1808calculates a new handoff activation time (e.g., THO_recalc) andpre-configures the target B×P 1806 for handoff before the new handoffactivation time (e.g., before THO_recalc).

The operations of steps 3-11 correspond to steps 1-9 of FIG. 17. Thus,these operations will be discussed briefly. At step 3, the source A×P1808 sends a Radio Connection Reconfiguration message to the UT 1802.The contents of the message are described herein, including the handoffactivation time. Optionally, the message may also contain measurementgap configuration information and measurement activation/deactivationtime. The message is sent to the UT 1802 sufficiently in advance of thehandoff activation time so that the UT 1802 has adequate time to receivethe message. The UT 1802 starts timer T-4. If T-4 expires (e.g., ahandoff failure occurs), then the UT 1802 performs the Radio ConnectionRe-establishment procedure. Also, if the source A×P 1808 does notreceive the measurement report from the UT 1802 in a timely manner, thenthe source A×P 1808 uses the old handoff activation time (e.g.,THO_a_priori) when configuring both the target B×P 1806 and UT 1802 forhandoff.

At step 4, based upon the single row of the satellite and celltransition table contained in the Radio Connection Reconfigurationmessage in Step 3, both the UT 1802 and the source A×P 1808simultaneously prepare for B×P handoff at the new handoff activationtime (e.g., THO_recalc).

At step 5, the UT 1802 resets the MAC state. The UT 1802 acquires thenew cell (e.g., FL synchronization).

Referring to FIG. 19, after the handoff activation+Inter-Cell Tune-awaytime, the target B×P 1806 sends an FLCC order to the UT 1802 containinga dedicated preamble signature in order to trigger the UT 1802 toperform a non-contention based Random Access procedure. This enables theUT 1802 to subsequently achieve RL synchronization.

At step 6, the UT 1802 sends a non-contention based Random AccessPreamble on the Random Access to the target B×P 1806. Upon receiving thenon-contention based Random Access Preamble from the UT 1802, the targetB×P 1806 validates the received signature sequence.

At step 7, the target B×P 1806 sends a Random Access Response to the UT1802 that is addressed to the appropriate RA-RNTI. The Random AccessResponse contains the paging area, RL grant (which includes a CQIrequest), and temporary UT-ID.

Upon receiving the RL grant+CQI request from the target B×P 1806 (step10A), the UT 1802 stops timer T-4 (e.g., the handoff is successful) andsends a CQI report to the target B×P 1806 (step 10B) and a RadioConnection Reconfiguration Complete message to the target B×P1806/source A×P 1808 (step 11). The Radio Connection ReconfigurationComplete message contains no IEs and is integrity protected andencrypted with the old keys (e.g., Kint and Kenc, respectively). Finalpacket data flow is represented by lines 1824, 1826, and 1828.

B×P Handoff—Failover

In an intra-GN, GN antenna failover, an antenna assembly serving thesatellite has failed. This case, one of two scenarios are possible. In afirst scenario, the UT experiences a brief interruption in connectivityand data service which is managed by the GN as a part of normaloperation (e.g., scheduling of FL and RL resources for the UT by the GN,HARQ retransmissions and ARQ retransmissions). In a second scenario, theUT experiences a loss of FL synchronization or there is a significantinterruption in connectivity and data service which results in a radiolink failure (RLF).

A×P Handoff

Inter-A×P handoffs may be performed for load-balancing purposes or fornon-stationary UTs that require an inter-A×P handoff due to a change inthe UT's location resulting in a crossing of an Administrative Regionboundary. An A×P handoff procedure comprises three distinct phases: A×Phandoff preparation, A×P handoff execution, and A×P handoff completion.

The following procedures may be used for A×P Handoff Preparation.

For Radio Control (RC) acknowledged mobile (AM) data bearers, if directforwarding of data applies, then tunnels may be established per RL-AMdata bearer (one way from source A×P to target A×P) for both forwardlink and reverse link data forwarding. Conversely, if indirectforwarding of data applies, then tunnels may be established per RL-AMdata bearer (one way from source A×P to target A×P via the GN) for bothforward link and reverse link data forwarding.

For RC unacknowledged mobile (UM) data bearers, if direct forwarding ofdata applies, then tunnels may be established per RL-UM data bearer (oneway from source A×P to target A×P) for forward link data forwardingonly. Reverse link data is not forwarded from source A×P to target A×Pbut instead is sent by the source A×P to the GN. Conversely, if indirectforwarding of data applies, then tunnels may be established per RL-UMdata bearer (one way from source A×P to target A×P) for forward linkdata forwarding only. Reverse link data is not forwarded from source A×Pto target A×P but instead is sent by the source A×P to the GN.

The following procedures may be used for A×P Handoff Execution.

For RL-AM data bearers, the reverse link forwarded data containssequence numbers (SNs). The forward link forwarded data may contain SNsor may not if the forward link data is received from the GN withouthaving been assigned a SN by the source A×P yet. The source A×P sendsboth forward link and reverse link SN and frame number (FN) informationto the target A×P. The MAC and RL states are reset.

For RL-UM data bearers, the forward link forwarded data may contain SNsor may not if the forward link data is received from the GN withouthaving been assigned a SN by the source A×P yet. If the forward linkforwarded data contains a SN, then the target A×P should send this datato the UT first (after resetting both the SN and FN). The state is reset(e.g., the forward link and reverse link SN and FN are reset). The MACand RL states are reset.

The following procedures may be used for Handoff Completion.

For RL-AM data bearers, the UT may send a list of missing/receivedforward link protocol data units (PDUs) to the target A×P and the targetA×P may send a list of missing/received reverse link PDUs to the UT. Forboth RL-AM and RL-UM data bearers, the forward link tunnels per databearer are switched from the source A×P to the target A×P and UTresources are released at the source AP.

FIGS. 20-22 illustrate an A×P handoff call flow without mobilitymanagement (MM) relocation and without GN relocation. FIG. 20 depictshandoff preparation. FIG. 21 depicts handoff execution. FIG. 22 depictshandoff completion. A description of the steps in the A×P handoff callflow follows.

Referring initially to FIG. 18, the call flow is between a UT 2002, asource B×P 2004, a target B×P 2006, a source A×P 2008, a target A×P2012, mobility management (MM) 2014 (e.g., a MM component), and a GN2010. Initial packet data flow is represented by lines 2016, 2018, and2020.

At step 1, the source A×P 2008 makes a decision to hand over the UT 2002to a target cell and a target A×P 2012 based on the satellite ephemerisinformation and beam patterns.

At step 2, the source A×P 2008 sends a Handoff Required message to theMM 2014 in order to request the preparation of resources at the targetA×P 2012. The message contains the paging area identifier (PAI) of thetarget A×P 2012 (so that the MM 2014 can determine to which target A×P2012 it should send the Handoff Request message in step 3), whether ornot a direct data forwarding path is available (e.g., via an appropriateinterface), and a source-to-target transparent container (passedtransparently through the MM 2014) that carries a Handoff PreparationInformation message which comprises the following: the UT's radioresource configuration in the source A×P 2008, the UT's securityconfiguration in the source A×P 2008, target cell ID (e.g., target B×PID indicating the beam to be prepared), and radio bearer information(including whether or not the source A×P 2008 proposes to do forwardlink data forwarding).

In step 3, the MM 2014 sends a Handoff Request message to the target A×P2012 in order to request the preparation of resources at the target A×P2012. The message contains the source-to-target transparent containercarried in the Handoff Required message (see Step 2), a list of databearers to be set up (e.g., quality of service (QoS) information, GNtunneling protocol (TP) addressing information per data bearer), andsecurity context information (e.g., one pair of NH, NCC for 1-hopsecurity during the target A×P's derivation of new security keys foruser plane traffic and radio signaling).

At step 4, upon receiving the Handoff Request message from the MM 2014,the target A×P 2012 decides that it can establish the UE context.

At step 5, the target A×P 2012 sends a Handoff Request Acknowledgemessage to the MM 2014 to inform the MM 2014 about the preparedresources at the target A×P 2012. The message contains atarget-to-source transparent container (passed transparently through theMM 2014) that carries a Handoff Command message to be used by the sourceA×P 2008 when constructing the Radio Connection Reconfiguration message(see step 8). The Handoff Request Acknowledge message also contains alist of data bearers to be setup, which includes the target A×P downlinkTP addressing information on a designated interface per data bearer(e.g., for data sent directly to the target A×P 2012 from the GN 2010,not via the source A×P 2008). The Handoff Request message may alsoinclude additional target A×P 2012 forward link TP addressinginformation per data bearer (if the source A×P 2008 proposed to doforward link data forwarding for a data bearer and the target A×P 2012accepts the proposal) and target A×P reverse link TP addressinginformation per data bearer (if the target A×P 2012 requests the sourceA×P 2008 to do reverse link data forwarding for an RL-AM data bearer).

At step 6, if indirect forwarding of data applies (e.g., via thedesignated interface), the MM 2014 sends a Create Indirect DataForwarding Tunnel Request message to the GN 2010. The message contains alist of data bearers which includes the following information per databearer: data bearer ID, the target A×P's tunnel ID and IP address forthe indirect forwarding of forward link data on a designated interface,and the target A×P's tunnel ID and IP address for the indirectforwarding of reverse link data on the designated interface, asapplicable. Subsequently, the GN 2010 sends a Create Indirect DataForwarding Tunnel Response message to the MM 2014. The message containsthe following information per data bearer: data bearer ID, the GN'stunnel ID and IP address for the indirect forwarding of forward linkdata on the designated interface, and the GN's tunnel ID and IP addressfor the indirect forwarding of reverse link data on the designatedinterface, as applicable.

At step 7, the MM 2014 sends a Handoff Command message to the source A×P2008 to inform the source A×P 2008 that resources for the handoff havebeen prepared at the target A×P 2012. The message contains thetarget-to-source transparent container carried in the Handoff RequestAcknowledge message (see Step 5) to be used by the source A×P 2008 whenconstructing the Radio Connection Reconfiguration message (see Step 8).The Handoff Command message also contains a list of data bearers to beset up. If direct forwarding of data applies (e.g., via an appropriateinterface), the message may contain the target A×P forward link TPaddressing information per data bearer (if the source A×P 2008 proposedto do forward link data forwarding for a data bearer and the target A×P2012 accepts the proposal), and target A×P reverse link TP addressinginformation per data bearer (if the target A×P 2012 requests the sourceA×P 2008 to do reverse link data forwarding for an RL-AM data bearer).If indirect forwarding of data applies (e.g., via the designatedinterface), the message may contain the GN forward link TP addressinginformation per data bearer (if the source A×P 2008 proposed to doforward link data forwarding for a data bearer and the target A×P 2012accepts the proposal), and GN reverse link TP addressing information perdata bearer (if the target A×P 2012 requests the source A×P 2008 to doreverse link data forwarding for an RL-AM data bearer). See Step 6.Also, the message contains a new satellite and cell transition table.Upon receiving the Handoff Command message, the source A×P 2008 freezesthe transmitter/receiver status for the UT's data bearers.

At step 8, the source A×P 2008 sends a Radio Connection Reconfigurationmessage to the UT 2002. The message contains a new UT-ID, the PCI andfrequency for the target B×P 2006, security information, radio resourcecommon and dedicated configuration information as needed (e.g., RandomAccess information, CQI reporting information), and target data bearerconfiguration information (if there are any changes from the currentconfiguration). The message also contains a new paging area identifierthat uniquely identifies the target A×P 2012. Upon receiving the RadioConnection Reconfiguration message from the source A×P 2008, the UEstarts timer T-4. If T-4 expires (e.g., a handoff failure occurs), thenthe UT 2002 performs the Radio Connection Re-establishment procedure.

At step 9, the UT 2002 derives the new KA×P, KUPenc, Kint, and Kenc tobe used when the UT 2002 performs the handoff to the target A×P 2012.

Referring to FIG. 21, for RL-AM data bearers, the UT 2002 resets the MACand RL states (step 10). For RL-UM data bearers, the UT 2002 resets theMAC, RL, and states. The UT 2002 subsequently acquires the new cell(e.g., FL synchronization).

At steps 11 and 12, the source A×P 2008 sends a UT Status Transfermessage to the target A×P 2012 via the MM 2014. The source A×P 2008sends this message to the target A×P 2012 only if at least one databearer is configured for RL-AM operation. The message contains thefollowing information per RL-AM data bearer: reverse link SN and FNreceiver status, forward link SN and FN transmitter status, and(optionally) the receive status of reverse link service data units(SDUs) (if the target A×P 2012 requested the source A×P 2008 to doreverse link data forwarding for an RL-AM data bearer and the source A×P2008 accepted the request). Also, for RL-AM and RL-UM data bearers, thesource A×P 2008 begins to forward in order forward link data (stored inthe source A×P 2008 data bearer buffers) to the target A×P 2012. ForRL-AM data bearers, this includes all forward link SDUs with their SNfor which successful delivery of the corresponding PDU was not confirmedby the UT 2002 (e.g., via RL Status PDU). For RL-AM and RL-UM databearers, this also includes new forward link data arriving on thedesignated interface from the GN 2010. For RL-AM data bearers for whichreverse link data forwarding applies, the source A×P 2008 begins toforward reverse link SDUs with their SN that have been receivedout-of-sequence to the target A×P 2012. For RL-AM data bearers for whichreverse link data forwarding does not apply, the source A×P 2008discards reverse link SDUs that have been received out-of-sequence. ForRL-UM data bearers, the source A×P 2008 sends reverse link SDUs thathave been received out-of-sequence to the GN 2010 via the designatedinterface. Note: If direct forwarding of data applies, the source A×P2008 forwards data to the target A×P 2012 on an appropriate interface.

If indirect forwarding of data applies, the source A×P 2008 forwardsdata 2022 to the target A×P 2012 on the designated interface via the GN2010. The forwarded data is stored in the target A×P data bearer buffers(step 12).

At step 12, the UT 2002 sends a contention-based Random Access Preambleon the Random Access to the target B×P 2006 (where the source B×P 2004and the target B×P 2006 may be the same entity). Upon receiving theRandom Access Preamble from the UT 2002, the target B×P 2006 validatesthe received signature sequence. If a dedicated preamble signature isavailable in the target B×P 2006 and the UT 2002 is assigned a dedicatedpreamble signature in Step 8, then the UT 2002 sends a contention-freeRandom Access Preamble on the Random Access to the target B×P 2006 and,consequently, there is no chance of a collision.

At step 14, the target B×P 2006 sends a Random Access Response to the UT2002 that is addressed to the appropriate RA-RNTI. The Random AccessResponse contains the paging area, RL grant, and temporary UT-ID.

In the operations of block 2030, the UT 2002 sends a Radio ConnectionReconfiguration Complete message to the target A×P 2012 (step 15). Themessage contains no IEs. The Radio Connection Reconfiguration Completemessage is integrity protected and encrypted with the new Kint and Kenc,respectively, and sent in conjunction with a UT-ID MAC control element(CE) and two new MAC control elements: a PAI MAC control element and alocation management information (LMI) MAC control element. The UT-ID MACcontrol element contains the UT-ID assigned to the UT 2002 by the targetA×P 2012 in the Radio Connection Reconfiguration message (see Step 8).The PAI MAC control element contains the PAI assigned to the UT 2002 bythe target A×P 2012 in Step 8. The LMI MAC control element contains theUT's latest location information. The target B×P 2006 parses the PAI MACcontrol element in order to determine to which A×P it should forward theRadio Connection Reconfiguration Complete message. The target B×P 2006may send a Handoff Notify message to the MM 2014 at this time (e.g.,instead of at step 19). The UT 2002 starts the Contention ResolutionTimer.

At step 16, the target B×P 2006 sends to the UT 2002 an RL grant for anew transmission. The RL grant is addressed to the UT-ID that the targetA×P 2012 assigned to the UT 2002 in the Radio Connection Reconfigurationmessage (see Step 8). Upon receiving the RL grant from the target B×P2006, the UT 2002 stops the Contention Resolution Timer and timer T-4.The UT 2002 may begin to send reverse link signaling on signaling radiobearers (e.g., SRB1 and SRB2) and reverse link data on all data radiobearers (DRBs). The UT 2002 may also begin to receive forward linksignaling on SRB1 and SRB2 and forward link forwarded data on all DRBs.

Referring now to FIG. 22, for RL-AM data bearers for which reverse linkdata forwarding applies, the target A×P 2012 sends a Status Reportmessage to the UT 2002 containing a list of missing and received reverselink PDUs (step 17). The target A×P 2012 uses the information in the UTStatus Transfer message from the source A×P 2008 via the MM 2014 (seeStep 11) to construct the Status Report. Upon receiving the StatusReport message from the target A×P 2012, the UT 2002 does not performretransmission of any PDU whose successful delivery is confirmed by theStatus Report message. After the reverse link PDU retransmissions havebeen successfully completed, the UT 2002 begins to send new RL-AMreverse link PDUs to the target A×P 2012. Since the reverse link SN ismaintained on an RL-AM data bearer basis, the target A×P 2012 uses awindows-based mechanism for in-sequence delivery and duplicationavoidance. For RL-UM data bearers, the UT 2002 begins to send new RL-UMreverse link PDUs to the target A×P 2012. The above packet data flow isrepresented by the arrows 2032, 2034, and 2036.

For all RL-AM data bearers for which the source A×P 2008 has configuredthe UT 2002 to send a Status Report on the reverse link duringre-establishment, the UT 2002 sends a Status Report message to thetarget A×P 2012 containing a list of missing and received forward linkPDUs (step 18). Upon receiving this message, the target A×P 2012 beginsto send forward link PDUs to the UE that have been forwarded to thetarget A×P 2012 by the source A×P 2008 with and without their SNs. Thispacket data flow is represented by the arrows 2038 and 2040. The targetA×P 2012 continues to do this until it receives one or more TP EndMarker packets from the source A×P 2008 for that RL-AM data bearer. Thetarget A×P 2012 does not perform retransmission of any PDU whosesuccessful delivery is confirmed by the Status Report message from theUT 2002. Since the forward link SN is maintained on an RL-AM data bearerbasis, the UT 2002 uses a windows-based mechanism for in-sequencedelivery and duplication avoidance. For RL-UM data bearers, the targetA×P 2012 begins to send forward link PDUs to the UT 2002 that have beenforwarded to the target A×P 2012 by the source A×P 2008 (withoutcontinuing their original SNs because the SN is not maintained on anRL-UM data bearer basis). The target A×P 2012 continues to do this untilit receives one or more TP End Marker packets from the source A×P 2008for each RL-UM data bearer.

Step 19 may occur immediately after Step 15. At step 19, the target A×P2012 sends a Handoff Notify message to the MM 2014 to inform the MM 2014that the UT 2002 has been identified in the target cell and the handoffhas been completed. The message contains the PAI of the target A×P 2012and the target cell ID (e.g., target B×P ID indicating the beam in whichthe UT 2002 has been identified).

At step 20, the MM 2014 sends a Modify Bearer Request message to the GN2010. The message contains a list of data bearers which includes thefollow information per data bearer: data bearer ID and the target A×P'stunnel ID and IP address for the forward link user plane (in order touniquely identify the UT's data bearers).

At step 21, the GN 2010 switches the forward link data path from thesource A×P 2008 to the target A×P 2012 and sends one or more TP EndMarker packets 2042 per data bearer to the source A×P 2008. The GN 2010also begins to send forward link data intended for the UT 2002 directlyto the target A×P 2012 (arrows 2044 and 2046). The source A×P 2008forwards the TP End Marker packet(s) per data bearer to the target A×P2012. Upon receiving the TP End Marker packet(s) per data bearer fromthe source A×P 2008, the target A×P 2012 may begin to send forward linkdata received directly from the GN 2010 to the UT 2002. Note: If directforwarding of data applies, the source A×P 2008 forwards the TP EndMarker packet(s) 2048 to the target A×P 2012 on an appropriateinterface. If indirect forwarding of data applies, the source A×P 2008forwards data to the target A×P 2012 via the GN 2010 (arrow 2050).

At step 22, the GN 2010 sends a Modify Bearer Response message to the MM2014. The message contains a list of data bearers which includes thefollowing information per data bearer: data bearer ID and cause (e.g.,request accepted).

At step 23A, the MM 2014 sends a UE Context Release Command message tothe source A×P 2008 to request the release of the UT-associatedS1-logical connection over the S1 interface. Subsequently, at step 23B,the source A×P 2008 sends a UE Context Release Command message to the MM2014 to confirm the release of the UT-associated logical connection overthe appropriate interface. At step 24, the source A×P 2008 releases theUT radio resources and context. At step 25, the indirect data forwardingtunnel request (from step 6) is deleted. Final packet data flow isrepresented by lines 2052, 2054, and 2056.

Use of Satellite and Cell Transition Table

In some implementations, an A×P may generate and/or update a satelliteand cell transition table, as needed, using one or more of: UT locationand/or speed, satellite location, satellite beam/cell patterns,satellite beam/cell turn on/off schedules, or satellite pointing error.The location and/or of a UT, if specified, may be sent by the UT viaRadio signaling messages. The locations of a satellite over time may beobtained from the ephemeris data. For example, in a given satelliteaccess network (SAN) that includes multiple GNs, the NOC/SOC in the SANmay provide the updated satellite ephemeris information to all A×Ps inthe SAN.

In some implementations, the system provides to a UT a single row of thesatellite and cell transition table (e.g., a row of Table 2 set forthabove) to be used for connected mode handoffs. For example, the sourceA×P/B×P could include the single row of the satellite and celltransition table in an information element (IE) of a Radio ConnectionReconfiguration message that is sent to the UT while the UT is still onthe serving cell. Thus, while a UT is being served by one cell/beam, theUT may receive satellite and cell transition information that the UT isto use to transition to another cell/beam.

Configuration Messages at B×P Handoff

As mentioned above, each satellite beam may be regarded as a separatecell with its own data and control channels, and signals. When a UT ishanding over from one to another cell, some of the radio configurationparameters that were valid for the source cell may change and need to beupdated for UT operation on the target cell.

The radio message used for radio reconfiguration of the radio parametersfor the serving cell is also used to deliver the updated configurationparameters for the target cell.

The A×P communicates the reconfiguration parameters for the target cellto the source cell (step 1 in FIG. 15, and also applicable to the RadioConnection Reconfiguration delivery in FIG. 16, FIG. 17, and FIG. 18).The reconfiguration message for the target cell is delivered to a UT bythe source cell before the handoff occurs, as depicted in the step 1 inFIG. 15. The transmission of the message needs to be done sufficientlyin advance of the handoff, so the UT has time to receive the message ina timely manner to allow for reliable transmission. Upon receiving thereconfiguration message for the target cell, the UT stores it andapplies the reconfiguration once it starts the communication on thetarget cell.

The handoff is performed based on the handoff transition table (Table3), and follows the procedures defined for B×P handoff. The newconfiguration is applied at the handoff time, so that the UT isappropriately configured for the new serving cell before the data andcontrol exchange starts.

The Radio Reconfiguration message for the target beam may include theradio parameters that are UT specific (dedicated) and cell specific(common). Those can be the following: Dedicated, MAC configuration,Parameters related to discontinuous reception (DRX), Power headroomreporting (PHR), Buffer status reporting (BSR) scheduling request (SR),HARQ, SPS configuration, Parameters for semi-persistent scheduling(periodicity, resources), PHY configuration, Dedicated PHY parametersrelated to the power control of data and control channels, CQIreporting, sounding reference signal (SRS), and SR, Random Accessconfiguration, UT-ID, PCI, Common Radio resource configuration, Commonparameters for Random Access (such as preamble info, power control,supervision info), Physical Random Access (such as root sequence infoand Physical Random Access configuration index), reference signal powerand power control, RL reference signals, ACK/NACK and CQI mapping, SRS(such as bandwidth and sub-frame configuration), p-Max (used to limitUTs' RL transmission power in the cell). Note that since the UT-ID isprovided to a UT for each serving cell, the 16 bit UT-ID may besufficient to uniquely address the provisioned number of about 5000 UTsper cell.

Radio Link Failure

During normal operation, when a UT is handed-off from one satellite orcell/beam to another satellite or cell/beam, the signaling for thehandoff is completed between the GN entity supporting the handoff andthe UT. If the UT loses communication with the GN before the handoffsignaling is completed, a radio link failure (RLF) may be declared(e.g., at the UT). RLF can occur in the system because of a UT losingconnection to a cell for various possible reasons—for example, fadingeffects due to rain or snow, or due to blocking by a building or a tree.In this case, the UT may employ an RLF recovery mechanism tore-establish communication with the GN. The RLF procedure tries tore-connect the UT to the same source cell or to a different (e.g.,target) cell.

FIG. 23 illustrates an example of a call flow for an RLF procedure. Thecall flow is between a UT 2302, a source B×P a target B×P 2304, and asource A×P or a target A×P 2306. A description of the steps of the callflow follows.

At step 1, radio link detection procedures are used to detect RLF (e.g.,problems with the radio link connection). This can be done either at thephysical layer (example: if SNR is lower than a certain threshold), orat the MAC layer (example: if a certain number of packets are decoded inerror), or at the RL layer (example: if maximum number of RLretransmissions has been reached for a message). The UT 2302 initiates aRadio Connection Re-establishment procedure by starting a targetsatellite and cell search and selection procedure.

After the UT 2302 acquires a suitable target satellite and cell (step2), the UT 2302 sends a contention-based Random Access Preamble on theRandom Access to the target B×P 2304 (step 3). Upon receiving the RandomAccess Preamble from the UT 2302, the target B×P 2304 validates thereceived signature sequence. The target B×P 2304 could be the same asthe source B×P (e.g., the UT 2302 chooses the same cell that it wasconnected to before RLF occurred).

At step 4, the target B×P 2304 sends a Random Access Response to the UT2302 that is addressed to the appropriate UT-ID. The Random AccessResponse contains the paging area, an RL grant, and a temporary UT-ID.

At step 5, the UT 2302 sends a Radio Connection Reestablishment Requestmessage in conjunction with two new MAC control elements (PAI MACcontrol element and LMI MAC control element) to the appropriate targetA×P 2306. The Radio Connection Reestablishment message contains the UT'sold UT-ID, old PCI and a MAC-I for verification during the RadioConnection Re-establishment procedure. The PAI MAC control elementcontains the most recent PAI assigned to the UT 2302 by the source A×P.The PAI belongs to the target A×P if the handoff was in progress beforeRLF; otherwise, the PAI belongs to the source A×P. The LMI MAC controlelement contains the UT's latest location information. The target B×P2304 parses the PAI MAC control element and LMI MAC control element todetermine to which A×P it should forward the Radio ConnectionReestablishment Request message. If the LMI MAC control elementindicates an Administrative Region not handled by the A×P mapped to thePAI MAC control element, then the target B×P 2304 forwards the RadioConnection Reestablishment Request message to the appropriate target A×P(which will result in a Radio Connection Re-establishment procedurefailure and cause the UT 2302 to initiate a NAS recover procedure (e.g.,a Service Request procedure)). The UT 2302 starts timer T-3. If T-3expires (e.g., the Radio Connection Re-establishment procedure fails),then the UT 2302 performs the NAS Service Request procedure.

At step 6, the target A×P 2306 sends a Radio Connection Reestablishmentmessage in conjunction with a UE Contention Resolution Identity MACcontrol element (in order to provide contention resolution) to the UT2302. The Radio Connection Reestablishment message contains securityconfiguration information that is used by the UT 2302 to derive newcontrol plane and user plane keys (see Step 7). The message may alsocontain SRB1 configuration information.

At step 7, the UT 2302 derives the new KA×P, KUPenc, Kint, and Kenc tobe used with the re-established radio connection.

At step 8, the UT 2302 sends a Radio Connection Reestablishment Completemessage to the target A×P 2306. The message contains no IEs and isintegrity protected and encrypted with the new Kint and Kenc,respectively.

At step 9, the target A×P 2306 sends a Radio Connection Reconfigurationmessage to the UT 2302. The message contains SRB2 and DRB configurationinformation.

At step 10, the UT 2302 sends a Radio Connection ReconfigurationComplete message to the target A×P 2306. The message contains no IEs.Final packet data flow is represented by lines 2312 and 2314.

Example Operations

With the above in mind, additional examples of operations that may beperformed by a UT and/or a GN in support of handoff of the UT will nowbe described with respect to FIGS. 24-38.

FIG. 24 is a diagram illustrating an example of a process 2400 forgenerating and using satellite handoff information in accordance withsome aspects of the disclosure. The process 2400 may take place within aprocessing circuit which may be located in a GN or some other suitableapparatus (device). In some implementations, the process 2400 representsoperations performed by the GN controller 250 of FIG. 2. In someimplementations, the process 2400 represents operations performed by theapparatus 4600 of FIG. 46 (e.g., by the processing circuit 4610). Ofcourse, in various aspects within the scope of the disclosure, theprocess 2400 may be implemented by any suitable apparatus capable ofsupporting communication-related operations.

At block 2402, a GN (or other suitable apparatus) optionally receivesinformation from a user terminal. For example, the GN may receive userterminal capabilities and location information.

At block 2404, the generation of satellite handoff information istriggered at the GN (or other suitable apparatus). This information maycomprise some or all of a satellite and beam/cell transition table. Forexample, the generation of the table may be triggered based on handoffof a user terminal to a satellite or based on receipt of a measurementmessage from the user terminal.

At block 2406, the GN (or other suitable apparatus) generates satellitehandoff information that specifies a handoff time for a particular beamof a particular satellite. For example, the information may be a tablethat indicates timing for transitioning between cells/beams andsatellites. In some aspects, the table is optionally based, in part, oninformation received from the user terminal at block 2402.

At block 2408, the GN (or other suitable apparatus) sends the satellitehandoff information to the user terminal.

At block 2410, the GN (or other suitable apparatus) performs handoffsfor the user terminal to different cells/beams and at least onesatellite based on the satellite handoff information.

FIG. 25 is a diagram illustrating an example of a process 2500 for usingsatellite handoff information in accordance with some aspects of thedisclosure. The process 2500 may take place within a processing circuitwhich may be located in a user terminal or some other suitable apparatus(device). In some implementations, the process 2500 representsoperations performed by the control processor 420 of FIG. 4. In someimplementations, the process 2500 represents operations performed by theapparatus 4900 of FIG. 49 (e.g., by the processing circuit 4910). Ofcourse, in various aspects within the scope of the disclosure, theprocess 2500 may be implemented by any suitable apparatus capable ofsupporting communication-related operations.

At block 2502, a user terminal (or other suitable apparatus) optionallysends a measurement message.

At block 2504, the user terminal (or other suitable apparatus) receivessatellite handoff information that specifies a handoff time for aparticular beam of a particular satellite. For example, the informationmay be a table that indicates timing for transitioning betweencells/beams and satellites.

At block 2506, the user terminal (or other suitable apparatus) performshandoffs to a particular beam of a particular satellite (e.g., todifferent cells/beams and at least one satellite) based on the satellitehandoff information.

FIG. 26 is a diagram illustrating an example of a process 2600 forsignaling user terminal capability information in accordance with someaspects of the disclosure. The process 2600 may take place within aprocessing circuit which may be located in a user terminal or some othersuitable apparatus (device). In some implementations, the process 2600represents operations performed by the control processor 420 of FIG. 4.In some implementations, the process 2600 represents operationsperformed by the apparatus 4900 of FIG. 49 (e.g., by the processingcircuit 4910). Of course, in various aspects within the scope of thedisclosure, the process 2600 may be implemented by any suitableapparatus capable of supporting communication-related operations.

At block 2602, the transmission of user terminal capability informationis triggered at a user terminal (or other suitable apparatus). Forexample, the transmission may be triggered as a result of an initialconnection to a satellite.

At block 2604, the user terminal (or other suitable apparatus) generatesa capabilities message. In some aspects, the message indicates whetherthe UT can sense multiple cells/beams and/or satellites and/or themessage indicates UT inter-cell/beam and/or inter-satellite tune time.

At block 2606, the user terminal (or other suitable apparatus) sends thecapabilities message to a GN.

FIG. 27 is a diagram illustrating an example of a process 2700 for usinguser terminal capabilities in accordance with some aspects of thedisclosure. The process 2700 may take place within a processing circuitwhich may be located in a GN or some other suitable apparatus (device).In some implementations, the process 2700 represents operationsperformed by the GN controller 250 of FIG. 2. In some implementations,the process 2700 represents operations performed by the apparatus 4600of FIG. 46 (e.g., by the processing circuit 4610). Of course, in variousaspects within the scope of the disclosure, the process 2700 may beimplemented by any suitable apparatus capable of supportingcommunication-related operations.

At block 2702, a GN (or other suitable apparatus) receives acapabilities message from a user terminal. This capabilities messageincludes user terminal capability information.

At block 2704, the GN (or other suitable apparatus) generates satellitehandoff information. For example, a table or a portion of a table may begenerated based, in part, on the user terminal capability information(e.g., tune times), user terminal location information, satellitemotion, ephemeris information, and a restriction due to incumbentsystems.

At block 2706, the GN (or other suitable apparatus) selects a handoffprocedure for the user terminal based, in part, on the user terminalcapability information. For example, monitoring for a measurementmessage from a user terminal may be enabled or disabled based on whetherthe user terminal is dual sense capable. Thus, an apparatus may enableor disable whether the apparatus monitors for a measurement messagebased on the user terminal capability information.

FIG. 28 is a diagram illustrating an example of a process 2800 forsignaling user terminal location information in accordance with someaspects of the disclosure. The process 2800 may take place within aprocessing circuit which may be located in a user terminal or some othersuitable apparatus (device). In some implementations, the process 2800represents operations performed by the control processor 420 of FIG. 4.In some implementations, the process 2800 represents operationsperformed by the apparatus 4900 of FIG. 49 (e.g., by the processingcircuit 4910). Of course, in various aspects within the scope of thedisclosure, the process 2800 may be implemented by any suitableapparatus capable of supporting communication-related operations.

At block 2802, the transmission of user terminal location information istriggered at a user terminal (or other suitable apparatus). This may bethe result of an initial connection, or based on whether the UT isbeyond a geographical boundary (geo-fencing), or based on whether anerror bound has been exceeded.

At block 2804, the user terminal (or other suitable apparatus) generatesa location message. In some aspects, the message may indicate thecurrent location if the UT is stationary, or indicate a motion vector ifthe UT is moving.

At block 2806, the user terminal (or other suitable apparatus) sends thelocation message to a GN.

FIG. 29 is a diagram illustrating an example of a process 2900 for usinguser terminal location information in accordance with some aspects ofthe disclosure. The process 2900 may take place within a processingcircuit which may be located in a GN or some other suitable apparatus(device). In some implementations, the process 2900 representsoperations performed by the GN controller 250 of FIG. 2. In someimplementations, the process 2900 represents operations performed by theapparatus 4600 of FIG. 46 (e.g., by the processing circuit 4610). Ofcourse, in various aspects within the scope of the disclosure, theprocess 2900 may be implemented by any suitable apparatus capable ofsupporting communication-related operations.

At block 2902, a GN (or other suitable apparatus) receives a locationmessage from a user terminal. This location message includes userterminal location information.

At block 2904, the GN (or other suitable apparatus) generates satellitehandoff information based, in part, on user terminal locationinformation. For example, if the UT is stationary, the GN may generate atable or a portion of a table based on the current UT location. Asanother example, if the UT is moving, the GN may generate the table (orportion) based on a UT motion vector.

FIG. 30 is a diagram illustrating an example of a user terminal handoffprocess 3000 in accordance with some aspects of the disclosure. Theprocess 3000 may take place within a processing circuit which may belocated in a user terminal or some other suitable apparatus (device). Insome implementations, the process 3000 represents operations performedby the control processor 420 of FIG. 4. In some implementations, theprocess 3000 represents operations performed by the apparatus 4900 ofFIG. 49 (e.g., by the processing circuit 4910). Of course, in variousaspects within the scope of the disclosure, the process 3000 may beimplemented by any suitable apparatus capable of supportingcommunication-related operations.

At block 3002, an upcoming user terminal handoff is indicated at a userterminal (or other suitable apparatus). For example, the handoff may beindicated based on satellite handoff information.

At block 3004, the user terminal (or other suitable apparatus) measuressatellite signals (e.g., signals from the satellites indicated in thesatellite handoff information).

At block 3006, the user terminal (or other suitable apparatus)determines whether to send a measurement message. In some aspects, thisdetermination may involve determining whether signals from the currentcell/beam and/or satellite or whether signals from the target cell/beamand/or satellite are inadequate.

At block 3008, if applicable, the user terminal (or other suitableapparatus) sends a measurement message and receives new satellitehandoff information. In some aspects, the message may includemeasurement data and/or a request to advance/retard handoff timing.Thus, in some aspects, the user terminal may send a measurement messagebased on the signals measured at block 3004 and receive the satellitehandoff information as a result of sending the measurement message.

At block 3010, the user terminal (or other suitable apparatus) hands-offto the target cell/beam and/or satellite according to the satellitehandoff information.

FIG. 31 is a diagram illustrating an example of a GN handoff process3100 in accordance with some aspects of the disclosure. The process 3100may take place within a processing circuit which may be located in a GNor some other suitable apparatus (device). In some implementations, theprocess 3100 represents operations performed by the GN controller 250 ofFIG. 2. In some implementations, the process 3100 represents operationsperformed by the apparatus 4600 of FIG. 46 (e.g., by the processingcircuit 4610). Of course, in various aspects within the scope of thedisclosure, the process 3100 may be implemented by any suitableapparatus capable of supporting communication-related operations.

At block 3102, a GN (or other suitable apparatus) receives a measurementmessage from a user terminal.

At block 3104, the GN (or other suitable apparatus) determines, based onthe measurement message, whether to modify the satellite handoffinformation.

At block 3106, if applicable, the GN (or other suitable apparatus)modifies the satellite handoff information (e.g., advances or retardstransition timing) and sends the modified satellite handoff informationto the user terminal.

At block 3108, the GN (or other suitable apparatus) conducts a handoffof the user terminal according to the satellite handoff information.

FIG. 32 is a diagram illustrating another example of an inter-satellitehandoff signaling process 3200 in accordance with some aspects of thedisclosure. The process 3200 may take place within a processing circuitwhich may be located in a GN, a user terminal, or some other suitableapparatuses (devices). In some implementations, the process 3200represents one or more operations performed by the GN controller 250 ofFIG. 2. In some implementations, the process 3200 represents one or moreoperations performed by the control processor 420 of FIG. 4. In someimplementations, the process 3200 represents one or more operationsperformed by the apparatus 4600 of FIG. 46 (e.g., by the processingcircuit 4610). In some implementations, the process 3200 represents oneor more operations performed by the apparatus 4900 of FIG. 49 (e.g., bythe processing circuit 4910). Of course, in various aspects within thescope of the disclosure, the process 3200 may be implemented by anysuitable apparatuses capable of supporting communication-relatedoperations.

At block 3202, a user terminal (or other suitable apparatus) connects toa first satellite controlled by a first NAC at a GN.

At block 3204, handoff of the user terminal (or other suitableapparatus) to a second satellite controlled by a second NAC at the GN isindicated.

At block 3206, the second NAC (or other suitable apparatus) generatessatellite handoff information for the user terminal.

At block 3208, the second NAC (or other suitable apparatus) sends thesatellite handoff information to the first NAC.

At block 3210, the first NAC (or other suitable apparatus) sends thesatellite handoff information to the user terminal.

At block 3212, the user terminal (or other suitable apparatus) ishanded-off to a second satellite according to the satellite handoffinformation.

FIG. 33 is a diagram illustrating an example of a process 3300 forsignaling ephemeris information in accordance with some aspects of thedisclosure. The process 3300 may take place within a processing circuitwhich may be located in a GN, a user terminal, or some other suitableapparatuses (devices). In some implementations, the process 3300represents one or more operations performed by the GN controller 250 ofFIG. 2. In some implementations, the process 3300 represents one or moreoperations performed by the control processor 420 of FIG. 4. In someimplementations, the process 3300 represents one or more operationsperformed by the apparatus 4600 of FIG. 46 (e.g., by the processingcircuit 4610). In some implementations, the process 3300 represents oneor more operations performed by the apparatus 4900 of FIG. 49 (e.g., bythe processing circuit 4910). Of course, in various aspects within thescope of the disclosure, the process 3300 may be implemented by anysuitable apparatuses capable of supporting communication-relatedoperations.

At block 3302, a GN (or other suitable apparatus) sends ephemerisinformation to a user terminal.

At block 3304, the user terminal (or other suitable apparatus) receivesthe ephemeris information.

At block 3306, the user terminal (or other suitable apparatus) uses theephemeris information to synchronize with a satellite.

FIG. 34 is a diagram illustrating an example of a radio link failureprocess 3400 in accordance with some aspects of the disclosure. Theprocess 3400 may take place within a processing circuit which may belocated in a user terminal or some other suitable apparatus (device). Insome implementations, the process 3400 represents operations performedby the control processor 420 of FIG. 4. In some implementations, theprocess 3400 represents operations performed by the apparatus 4900 ofFIG. 49 (e.g., by the processing circuit 4910). Of course, in variousaspects within the scope of the disclosure, the process 3400 may beimplemented by any suitable apparatus capable of supportingcommunication-related operations.

At block 3402, a user terminal (or other suitable apparatus) losesconnectivity to a cell/beam or a satellite.

At block 3404, the user terminal (or other suitable apparatus) entersradio link failure mode.

At block 3406, the user terminal (or other suitable apparatus)identifies an alternate cell/beam and/or satellite (e.g., based onephemeris information stored at the user terminal).

At block 3408, the user terminal (or other suitable apparatus)establishes a connection using the alternate cell/beam and/or satellite.

At block 3410, the user terminal (or other suitable apparatus)communicates with a GN via the new connection.

At block 3412, the user terminal (or other suitable apparatus) exitsradio link failure mode.

FIG. 35 is a diagram illustrating an example of a measurementgap-related process 3500 in accordance with some aspects of thedisclosure. The process 3500 may take place within a processing circuitwhich may be located in a GN or some other suitable apparatus (device).In some implementations, the process 3500 represents operationsperformed by the GN controller 250 of FIG. 2. In some implementations,the process 3500 represents operations performed by the apparatus 4600of FIG. 46 (e.g., by the processing circuit 4610). Of course, in variousaspects within the scope of the disclosure, the process 3500 may beimplemented by any suitable apparatus capable of supportingcommunication-related operations.

At block 3502, a GN (or other suitable apparatus) determines whether ameasurement gap is needed for measuring satellite signals.

At block 3504, if a measurement gap is not needed, the GN (or othersuitable apparatus) does not include a tune-away time in the satellitehandoff information.

At block 3506, if a measurement gap is needed, the GN (or other suitableapparatus) determines the measurement gap to be used for measuringsatellite signals.

At block 3508, the GN (or other suitable apparatus) sends informationindicative of the measurement gap to a user terminal.

FIG. 36 is a diagram illustrating an example of a measurementgap-related process 3600 in accordance with some aspects of thedisclosure. The process 3600 may take place within a processing circuitwhich may be located in a user terminal or some other suitable apparatus(device). In some implementations, the process 3600 representsoperations performed by the control processor 420 of FIG. 4. In someimplementations, the process 3600 represents operations performed by theapparatus 4900 of FIG. 49 (e.g., by the processing circuit 4910). Ofcourse, in various aspects within the scope of the disclosure, theprocess 3600 may be implemented by any suitable apparatus capable ofsupporting communication-related operations.

At block 3602, a user terminal (or other suitable apparatus) receivesinformation indicative of a measurement gap for measuring satellitesignals (e.g., from a GN).

At block 3604, the user terminal (or other suitable apparatus) measuressignals from at least one satellite during the measurement gap(indicated by the received information).

FIG. 37 is a diagram illustrating an example of a user queue process3700 in accordance with some aspects of the disclosure. The process 3700may take place within a processing circuit which may be located in a GNor some other suitable apparatus (device). In some implementations, theprocess 3700 represents operations performed by the GN controller 250 ofFIG. 2. In some implementations, the process 3700 represents operationsperformed by the apparatus 4600 of FIG. 46 (e.g., by the processingcircuit 4610). Of course, in various aspects within the scope of thedisclosure, the process 3700 may be implemented by any suitableapparatus capable of supporting communication-related operations.

At block 3702, a GN (or other suitable apparatus) determines a time ofhandoff of a user terminal.

At block 3704, the GN (or other suitable apparatus) transfers at leastone user queue prior to the handoff.

FIG. 38 is a diagram illustrating an example of a random access process3800 in accordance with some aspects of the disclosure. The process 3800may take place within a processing circuit which may be located in auser terminal or some other suitable apparatus (device). In someimplementations, the process 3800 represents operations performed by thecontrol processor 420 of FIG. 4. In some implementations, the process3800 represents operations performed by the apparatus 4900 of FIG. 49(e.g., by the processing circuit 4910). Of course, in various aspectswithin the scope of the disclosure, the process 3800 may be implementedby any suitable apparatus capable of supporting communication-relatedoperations.

At block 3802, a user terminal (or other suitable apparatus) receives adedicated preamble signature (e.g., a UT receives a dedicated preamblesignature from a GN in a control channel order).

At block 3804, the user terminal (or other suitable apparatus) performsa non-contention-based random access procedure using the dedicatedpreamble signature.

First Example Apparatus

FIG. 39 illustrates a block diagram of an example hardwareimplementation of an apparatus 3900 configured to communicate accordingto one or more aspects of the disclosure. For example, the apparatus3900 could embody or be implemented within a UT or some other type ofdevice that supports satellite communication. Thus, in some aspects, theapparatus 3900 could be an example of the UT 400 or the UT 401 ofFIG. 1. In various implementations, the apparatus 3900 could embody orbe implemented within a satellite system component, a vehicularcomponent, or any other electronic device having circuitry.

The apparatus 3900 includes a communication interface 3902 (e.g., atleast one transceiver), a storage medium 3904, a user interface 3906, amemory device (e.g., a memory circuit) 3908, and a processing circuit3910 (e.g., at least one processor). In various implementations, theuser interface 3906 may include one or more of: a keypad, a display, aspeaker, a microphone, a touchscreen display, of some other circuitryfor receiving an input from or sending an output to a user.

These components can be coupled to and/or placed in electricalcommunication with one another via a signaling bus or other suitablecomponent, represented generally by the connection lines in FIG. 39. Thesignaling bus may include any number of interconnecting buses andbridges depending on the specific application of the processing circuit3910 and the overall design constraints. The signaling bus linkstogether various circuits such that each of the communication interface3902, the storage medium 3904, the user interface 3906, and the memorydevice 3908 are coupled to and/or in electrical communication with theprocessing circuit 3910. The signaling bus may also link various othercircuits (not shown) such as timing sources, peripherals, voltageregulators, and power management circuits, which are well known in theart, and therefore, will not be described any further.

The communication interface 3902 provides a means for communicating withother apparatuses over a transmission medium. In some implementations,the communication interface 3902 includes circuitry and/or programmingadapted to facilitate the communication of information bi-directionallywith respect to one or more communication devices in a network. In someimplementations, the communication interface 3902 is adapted tofacilitate wireless communication of the apparatus 3900. In theseimplementations, the communication interface 3902 may be coupled to oneor more antennas 3912 as shown in FIG. 39 for wireless communicationwithin a wireless communication system. The communication interface 3902can be configured with one or more standalone receivers and/ortransmitters, as well as one or more transceivers. In the illustratedexample, the communication interface 3902 includes a transmitter 3914and a receiver 3916. The communication interface 3902 serves as oneexample of a means for receiving and/or means transmitting.

The memory device 3908 may represent one or more memory devices. Asindicated, the memory device 3908 may maintain idle mode handoffinformation 3918 along with other information used by the apparatus3900. In some implementations, the memory device 3908 and the storagemedium 3904 are implemented as a common memory component. The memorydevice 3908 may also be used for storing data that is manipulated by theprocessing circuit 3910 or some other component of the apparatus 3900.

The storage medium 3904 may represent one or more computer-readable,machine-readable, and/or processor-readable devices for storingprogramming, such as processor executable code or instructions (e.g.,software, firmware), electronic data, databases, or other digitalinformation. The storage medium 3904 may also be used for storing datathat is manipulated by the processing circuit 3910 when executingprogramming. The storage medium 3904 may be any available media that canbe accessed by a general purpose or special purpose processor, includingportable or fixed storage devices, optical storage devices, and variousother mediums capable of storing, containing or carrying programming.

By way of example and not limitation, the storage medium 3904 mayinclude a magnetic storage device (e.g., hard disk, floppy disk,magnetic strip), an optical disk (e.g., a compact disc (CD) or a digitalversatile disc (DVD)), a smart card, a flash memory device (e.g., acard, a stick, or a key drive), a random access memory (RAM), a readonly memory (ROM), a programmable ROM (PROM), an erasable PROM (EPROM),an electrically erasable PROM (EEPROM), a register, a removable disk,and any other suitable medium for storing software and/or instructionsthat may be accessed and read by a computer. The storage medium 3904 maybe embodied in an article of manufacture (e.g., a computer programproduct). By way of example, a computer program product may include acomputer-readable medium in packaging materials. In view of the above,in some implementations, the storage medium 3904 may be a non-transitory(e.g., tangible) storage medium.

The storage medium 3904 may be coupled to the processing circuit 3910such that the processing circuit 3910 can read information from, andwrite information to, the storage medium 3904. That is, the storagemedium 3904 can be coupled to the processing circuit 3910 so that thestorage medium 3904 is at least accessible by the processing circuit3910, including examples where at least one storage medium is integralto the processing circuit 3910 and/or examples where at least onestorage medium is separate from the processing circuit 3910 (e.g.,resident in the apparatus 3900, external to the apparatus 3900,distributed across multiple entities, etc.).

Programming stored by the storage medium 3904, when executed by theprocessing circuit 3910, causes the processing circuit 3910 to performone or more of the various functions and/or process operations describedherein. For example, the storage medium 3904 may include operationsconfigured for regulating operations at one or more hardware blocks ofthe processing circuit 3910, as well as to utilize the communicationinterface 3902 for wireless communication utilizing their respectivecommunication protocols.

The processing circuit 3910 is generally adapted for processing,including the execution of such programming stored on the storage medium3904. As used herein, the terms “code” or “programming” shall beconstrued broadly to include without limitation instructions,instruction sets, data, code, code segments, program code, programs,programming, subprograms, software modules, applications, softwareapplications, software packages, routines, subroutines, objects,executables, threads of execution, procedures, functions, etc., whetherreferred to as software, firmware, middleware, microcode, hardwaredescription language, or otherwise.

The processing circuit 3910 is arranged to obtain, process and/or senddata, control data access and storage, issue commands, and control otherdesired operations. The processing circuit 3910 may include circuitryconfigured to implement desired programming provided by appropriatemedia in at least one example. For example, the processing circuit 3910may be implemented as one or more processors, one or more controllers,and/or other structure configured to execute executable programmingExamples of the processing circuit 3910 may include a general purposeprocessor, a digital signal processor (DSP), an application-specificintegrated circuit (ASIC), a field programmable gate array (FPGA) orother programmable logic component, discrete gate or transistor logic,discrete hardware components, or any combination thereof designed toperform the functions described herein. A general purpose processor mayinclude a microprocessor, as well as any conventional processor,controller, microcontroller, or state machine. The processing circuit3910 may also be implemented as a combination of computing components,such as a combination of a DSP and a microprocessor, a number ofmicroprocessors, one or more microprocessors in conjunction with a DSPcore, an ASIC and a microprocessor, or any other number of varyingconfigurations. These examples of the processing circuit 3910 are forillustration and other suitable configurations within the scope of thedisclosure are also contemplated.

According to one or more aspects of the disclosure, the processingcircuit 3910 may be adapted to perform any or all of the features,processes, functions, operations and/or routines for any or all of theapparatuses described herein. For example, the processing circuit 3910may be configured to perform any of the steps, functions, and/orprocesses described with respect to FIGS. 1-9 and 40-42. As used herein,the term “adapted” in relation to the processing circuit 3910 may referto the processing circuit 3910 being one or more of configured, used,implemented, and/or programmed to perform a particular process,function, operation and/or routine according to various featuresdescribed herein.

The processing circuit 3910 may be a specialized processor, such as anapplication-specific integrated circuit (ASIC) that serves as a meansfor (e.g., structure for) carrying out any one of the operationsdescribed in conjunction with FIGS. 1-9 and 40-42. The processingcircuit 3910 serves as one example of a means for transmitting and/or ameans for receiving. In some implementations, the processing circuit3910 may provide and/or incorporate, at least in part, the functionalityof the control processor 420 of FIG. 4.

According to at least one example of the apparatus 3900, the processingcircuit 3910 may include one or more of a circuit/module for identifying3920, a circuit/module for determining whether to send 3922, acircuit/module for sending 3924, a circuit/module for receiving 3926, acircuit/module for handing off 3928, or a circuit/module for determininglocation information 3930. In various implementations, thecircuit/module for identifying 3920, the circuit/module for determiningwhether to send 3922, the circuit/module for sending 3924, thecircuit/module for receiving 3926, the circuit/module for handing off3928, or the circuit/module for determining location information 3930may provide and/or incorporate, at least in part, the functionality ofthe control processor 420 of FIG. 4.

As mentioned above, programming stored by the storage medium 3904, whenexecuted by the processing circuit 3910, causes the processing circuit3910 to perform one or more of the various functions and/or processoperations described herein. For example, the programming may cause theprocessing circuit 3910 to perform the various functions, steps, and/orprocesses described herein with respect to FIGS. 1-9 and 40-42 invarious implementations. As shown in FIG. 39, the storage medium 3904may include one or more of code for identifying 3932, code fordetermining whether to send 3934, code for sending 3936, code forreceiving 3938, code for handing off 3940, or code for determininglocation information 3942. In various implementations, the code foridentifying 3932, the code for determining whether to send 3934, thecode for sending 3936, the code for receiving 3938, the code for handingoff 3940, or the code for determining location information 3942 may beexecuted or otherwise used to provide the functionality described hereinfor the circuit/module for identifying 3920, the circuit/module fordetermining whether to send 3922, the circuit/module for sending 3924,the circuit/module for receiving 3926, the circuit/module for handingoff 3928, or the circuit/module for determining location information3930.

The circuit/module for identifying 3920 may include circuitry and/orprogramming (e.g., code for identifying 3932 stored on the storagemedium 4604) adapted to perform several functions relating to, forexample, identifying information associated with at least one handoffentry. In some aspects, the circuit/module for identifying 3920 (e.g., ameans for identifying) may correspond to, for example, a processingcircuit.

In some implementations, the circuit/module for identifying 3920identifies a time associated with a handoff entry. For example, thecircuit/module for identifying 3920 may identify a time based on an idlemode handoff table (e.g., Table 1). Here, the idle mode handoff tablemay include entries that indicate a start time for a handoff to aparticular satellite. To this end, the circuit/module for identifying3920 acquires the entry information (e.g., from the memory device 3908,the circuit/module for receiving 3926, or some other component of theapparatus 3900). The circuit/module for identifying 3920 may thenprocess the information to determine a time (e.g., a frame number)associated with the entry. The circuit/module for identifying 3920 thengenerates an indication of this determination (e.g., indicative of thetime) and sends the indication to a component of the apparatus 3900(e.g., the circuit/module for determining whether to send 3922, thememory device 3908, or some other component).

In some implementations, the circuit/module for identifying 3920identifies a quantity of valid entries in a set of handoff entries. Forexample, the circuit/module for identifying 3920 may determine how manyvalid entries remain in an idle mode handoff table (e.g., Table 1). Tothis end, the circuit/module for identifying 3920 acquires the handoffentry information (e.g., from the memory device 3908, the circuit/modulefor receiving 3926, or some other component of the apparatus 3900). Insome scenarios, the circuit/module for identifying 3920 may process theinformation to determine the number of valid entries remaining in atable (e.g., in the case where entries remain in the table after theyexpire). For example, the circuit/module for identifying 3920 maycompare a time value (e.g., a handoff time) for each entry with thecurrent time and thereby determine which entries correspond to a timethat has not yet passed. In some scenarios, the circuit/module foridentifying 3920 may process the information to determine the totalnumber of entries remaining (e.g., in the case where entries are removedfrom the table as they expire). In either case, the circuit/module foridentifying 3920 generates an indication of this determination (e.g., acount indicative of the determined quantity) and sends the indication toa component of the apparatus 3900 (e.g., the circuit/module fordetermining whether to send 3922, the memory device 3908, or some othercomponent).

The circuit/module for determining whether to send 3922 may includecircuitry and/or programming (e.g., code for determining whether to send3934 stored on the storage medium 3904) adapted to perform severalfunctions relating to, for example, determining whether to sendinformation. In some aspects, the circuit/module for determining whetherto send 3922 (e.g., a means for determining whether to send) maycorrespond to, for example, a processing circuit.

In some implementations, the information to be sent may include arequest for an updated set of handoff entries. In some scenarios, thecircuit/module for determining whether to send 3922 obtains informationthat is used to make a send decision (e.g., from the circuit/module foridentifying 3920, the memory device 3908, or some other component).

In some scenarios, the circuit/module for determining whether to send3922 may obtain an indication of a time associated with a particularentry of a set of handoff entries. In this case, the circuit/module fordetermining whether to send 3922 may determine whether to send a requestbased on whether the time indicates that the set of handoff entriesshould be updated (e.g., due to the number of valid entries in the tablerunning low). For example, the sending of a request may be triggered ifthe difference between the current time and the indicated time is lessthan a threshold period of time.

In some scenarios, the circuit/module for determining whether to send3922 may obtain an indication of the quantity of valid entries in a setof handoff entries. In this case, the circuit/module for determiningwhether to send 3922 may determine whether to send a request based onwhether the quantity indicates that the set of handoff entries should beupdated (e.g., due to the number of valid entries in the table runninglow). For example, the sending of a request may be triggered if thenumber of valid entries is less than a threshold count (e.g., 1 or 2 orsome other quantity).

In either scenario, the circuit/module for determining whether to send3922 generates an indication of the above determination and sends theindication to the circuit/module for sending 3924, the memory device3908, or some other component of the apparatus 3900.

The circuit/module for sending 3924 may include circuitry and/orprogramming (e.g., code for sending 3936 stored on the storage medium3904) adapted to perform several functions relating to, for example,sending (e.g., outputting or transmitting) information. In someimplementations, the circuit/module for sending 3924 may obtain anindication that triggers sending (e.g., from the circuit/module fordetermining whether to send 3922, the memory device 3908, or some othercomponent of the apparatus 3900). In some implementations, thecircuit/module for sending 3924 may obtain information to be sent (e.g.,a request message, an indication, location information, etc.) from thecircuit/module for identifying 3920, the circuit/module for determininglocation information 3930, the memory device 3908 or some othercomponent of the apparatus 3900 and process the information (e.g.,encode the information for transmission). In some scenarios, thecircuit/module for sending 3924 provides the information to anothercomponent (e.g., the transmitter 3914, the communication interface 3902,or some other component) that will send the information to anotherdevice. In some scenarios (e.g., if the circuit/module for sending 3924includes a transmitter), the circuit/module for sending 3924 transmitsthe information directly to another device (e.g., the ultimatedestination) via radio frequency signaling or some other type ofsignaling suitable for the applicable communication medium.

The circuit/module for sending 3924 (e.g., a means for sending) may takevarious forms. In some aspects, the circuit/module for sending 3924 maycorrespond to, for example, a processing circuit as discussed herein. Insome aspects, the circuit/module for sending 3924 may correspond to, forexample, an interface (e.g., a bus interface, a send interface, or someother type of signal interface), a communication device, a transceiver,a transmitter, or some other similar component as discussed herein. Insome implementations, the communication interface 3902 includes thecircuit/module for sending 3924 and/or the code for sending 3936. Insome implementations, the circuit/module for sending 3924 and/or thecode for sending 3936 is configured to control the communicationinterface 3902 (e.g., a transceiver or a transmitter) to transmitinformation.

The circuit/module for receiving 3926 may include circuitry and/orprogramming (e.g., code for receiving 3938 stored on the storage medium3904) adapted to perform several functions relating to for example,receiving information. The information may include, without limitation,an indication, a set of handoff entries, a handoff table, etc. In somescenarios, the circuit/module for receiving 3926 may obtain information(e.g., from the communication interface 3902, the memory device, or someother component of the apparatus 3900) and process (e.g., decode) theinformation. In some scenarios (e.g., if the circuit/module forreceiving 3926 is or includes an RF receiver), the circuit/module forreceiving 3926 may receive information directly from a device thattransmitted the information. In either case, the circuit/module forreceiving 3926 may output the obtained information to another componentof the apparatus 3900 (e.g., the circuit/module for handing off 3928,the memory device 3908, or some other component).

The circuit/module for receiving 3926 (e.g., a means for receiving) maytake various forms. In some aspects, the circuit/module for receiving3926 may correspond to, for example, an interface (e.g., a businterface, a send/receive interface, or some other type of signalinterface), a communication device, a transceiver, a receiver, or someother similar component as discussed herein. In some implementations,the communication interface 3902 includes the circuit/module forreceiving 3926 and/or the code for receiving 3938. In someimplementations, the circuit/module for receiving 3926 and/or the codefor receiving 3938 is configured to control the communication interface3902 (e.g., a transceiver or a receiver) to receive information.

The circuit/module for handing off 3928 may include circuitry and/orprogramming (e.g., code for handing off 3940 stored on the storagemedium 3904) adapted to perform several functions relating to, forexample, performing a handoff for a user terminal to a target cell,beam, or satellite. In some aspects, the circuit/module for handing off3928 (e.g., a means for handing off) may correspond to, for example, aprocessing circuit.

In some implementations, the circuit/module for handing off 3928identifies one or more of a target satellite, a target cell, or a targetbeam based on a set of handoff entries (e.g., Table 1). To this end, thecircuit/module for handing off 3928 may collect this information,process the information to identify the target (and, optionally, atleast one carrier frequency of the target), and reconfigurecommunication parameters of the apparatus 3900 to cause the userterminal to communicate with the target. For example, the circuit/modulefor handing off 3928 can determine whether to handoff to a particularcell of a particular satellite at a particular time based on timinginformation in the set of handoff entries. As another example, thecircuit/module for handing off 3928 can determine whether to handoff toa particular cell of a particular satellite on a particular carrierfrequency based on frequency information in the set of handoff entries.If handoff is indicated, the circuit/module for handing off 3928 cancommence handoff signaling accordingly.

The circuit/module for determining location information 3930 may includecircuitry and/or programming (e.g., code for determining locationinformation 3942 stored on the storage medium 3904) adapted to performseveral functions relating to, for example, determining locationinformation for an apparatus. In some aspects, the circuit/module fordetermining location information 3930 (e.g., a means for determininglocation information) may correspond to, for example, a processingcircuit.

In some scenarios, the circuit/module for determining locationinformation 3930 obtains information that relates to at least onelocation of the apparatus. For example, the circuit/module fordetermining location information 3930 may obtain global positioningsystem (GPS) coordinates from a GPS receiver indicative of a currentlocation of the apparatus. As another example, the circuit/module fordetermining location information 3930 may obtain a set of globalpositioning system (GPS) coordinates from a GPS receiver indicative ofmovement of the apparatus (e.g., a path along which the apparatus hastraveled). In some scenarios, this obtained information may constitutethe location information. In some scenarios, the circuit/module fordetermining location information 3930 may process this obtainedinformation to generate the location information (e.g., by generating anindication of speed or a vector indicative of movement). Finally, thecircuit/module for determining location information 3930 outputs thelocation information to the circuit/module for sending 3924, the memorydevice 3908, or some other component of the apparatus 3900.

First Example Process

FIG. 40 illustrates a process 4000 for communication in accordance withsome aspects of the disclosure. The process 4000 may take place within aprocessing circuit (e.g., the processing circuit 3910 of FIG. 39), whichmay be located in a UT or some other suitable apparatus. Of course, invarious aspects within the scope of the disclosure, the process 4000 maybe implemented by any suitable apparatus capable of supportingcommunication-related operations.

At block 4002, an apparatus (e.g., a UT) identifies a time associatedwith a particular entry of a set of handoff entries. In some aspects,the set of handoff entries may identify a set of satellites for handoffof the apparatus. In some aspects, the time may include a start time fora handoff to one satellite of the set of satellites. In some aspects,the particular entry may include a last entry of the set of handoffentries.

The set of handoff entries may take different forms in differentimplementations. In some aspects, the set of handoff entries may includean idle mode handoff table. In some aspects, the time may indicate whenthe apparatus is to handoff to one satellite of the set of satelliteswhile the apparatus is in an idle mode. In some aspects, the idle modehandoff table may include, for each satellite, a time for the apparatuswhen in idle mode to handoff to the satellite. In some aspects, the setof satellites may be for an idle mode operation of the apparatus. Insome aspects, the set of handoff entries may include, for eachsatellite, a time for the apparatus when in idle mode to handoff to thesatellite.

At block 4004, the apparatus determines, based on the identified time ofblock 4002, whether to send a request for an updated set of handoffentries.

At block 4006, the apparatus sends the request for an updated set ofhandoff entries if the determination is to send the request. In someaspects, the request may be communicated when the apparatus establishesa Radio connection with a ground network (GN).

In some aspects, an apparatus may perform any of the operationsdiscussed above for FIG. 40, or any combination thereof.

Second Example Process

FIG. 41 illustrates a process 4100 for communication in accordance withsome aspects of the disclosure. The process 4100 may take place within aprocessing circuit (e.g., the processing circuit 3910 of FIG. 39), whichmay be located in a UT or some other suitable apparatus. Of course, invarious aspects within the scope of the disclosure, the process 4100 maybe implemented by any suitable apparatus capable of supportingcommunication-related operations.

At block 4102, an apparatus (e.g., a UT) identifies a quantity of validentries in a set of handoff entries. In some aspects, the set of handoffentries may identify a set of satellites for handoff of the apparatus.

The set of handoff entries may take different forms in differentimplementations. In some aspects, the set of handoff entries may includean idle mode handoff table. In some aspects, the set of satellites maybe for an idle mode operation of the apparatus. In some aspects, the setof handoff entries may identify times at which the apparatus when inidle mode is to handoff to each satellite of the set of satellites. Insome aspects, the set of handoff entries may include, for eachsatellite, a time for the apparatus when in idle mode to handoff to thesatellite.

At block 4104, the apparatus determines, based on the identifiedquantity, whether to send a request for an updated set of handoffentries. In some aspects, the determination of whether to send therequest for an updated set of handoff entries may include determiningwhether the set of handoff entries includes only one valid entry.

At block 4106, the apparatus sends the request for an updated set ofhandoff entries if the determination is to send the request. In someaspects, the request may be communicated when the apparatus establishesa Radio connection with a ground network (GN).

In some aspects, an apparatus may perform any of the operationsdiscussed above for FIG. 41, or any combination thereof.

Third Example Process

FIG. 42 illustrates a process 4200 for communication in accordance withsome aspects of the disclosure. One or more aspects of the process 4200may be used in conjunction with (e.g., in addition to or as part of) theprocess 4000 of FIG. 40 or the process 4100 of FIG. 41. The process 4200may take place within a processing circuit (e.g., the processing circuit3910 of FIG. 39), which may be located in a UT or some other suitableapparatus. Of course, in various aspects within the scope of thedisclosure, the process 4200 may be implemented by any suitableapparatus capable of supporting communication-related operations.

At optional block 4202, an apparatus (e.g., a UT) may determine locationinformation for an apparatus (e.g., for the UT).

At block 4204, the apparatus sends a request for an updated set ofhandoff entries (e.g., to a GN).

At optional block 4206, the apparatus may send information inconjunction with the request. For example, the apparatus may send thelocation information for the apparatus, an indication of a timeassociated with a particular entry of a set of handoff entries, anindication of a time of validity associated with the set of handoffentries, or any combination thereof.

At block 4208, the apparatus receives the updated set of handoff entries(e.g. after sending the request at block 4202).

At optional block 4210, the apparatus may receive an indication of atleast one carrier frequency at which a next cell that provides coveragefor the apparatus will be transmitting. For example, a UT may receivefrom a GN a nextCellTransmitFreq parameter (e.g., via a BIB message). Asdiscussed above, this parameter may include a list of possiblefrequencies, a single frequency, and so on.

At block 4212, the apparatus hands-off to a satellite identified by theupdated set of handoff entries at a time indicated by the updated set ofhandoff entries. In scenarios that use block 4210, this handoff may beconducted on the indicated at least one carrier frequency.

In some aspects, an apparatus may perform any of the operationsdiscussed above for FIG. 42, or any combination thereof.

Second Example Apparatus

FIG. 43 illustrates a block diagram of an example hardwareimplementation of another apparatus 4300 configured to communicateaccording to one or more aspects of the disclosure. For example, theapparatus 4300 could embody or be implemented within a GN or some othertype of device that supports wireless communication. Thus, in someaspects, the apparatus 4300 could be an example of the GN 200 or the GN201 of FIG. 1. In various implementations, the apparatus 4300 couldembody or be implemented within a gateway, a ground station, a vehicularcomponent, or any other electronic device having circuitry.

The apparatus 4300 includes a communication interface (e.g., at leastone transceiver) 4302, a storage medium 4304, a user interface 4306, amemory device 4308 (e.g., storing idle mode handoff information 4318),and a processing circuit (e.g., at least one processor) 4310. In variousimplementations, the user interface 4306 may include one or more of: akeypad, a display, a speaker, a microphone, a touchscreen display, ofsome other circuitry for receiving an input from or sending an output toa user. The communication interface 4302 may be coupled to one or moreantennas 4312, and may include a transmitter 4314 and a receiver 4316.In general, the components of FIG. 43 may be similar to correspondingcomponents of the apparatus 3900 of FIG. 39.

According to one or more aspects of the disclosure, the processingcircuit 4310 may be adapted to perform any or all of the features,processes, functions, operations and/or routines for any or all of theapparatuses described herein. For example, the processing circuit 4310may be configured to perform one or more of the steps, functions, and/orprocesses described with respect to FIGS. 1-9, 44, and 45. As usedherein, the term “adapted” in relation to the processing circuit 4310may refer to the processing circuit 4310 being one or more ofconfigured, employed, implemented, and/or programmed to perform aparticular process, function, operation and/or routine according tovarious features described herein.

The processing circuit 4310 may be a specialized processor, such as anapplication specific integrated circuit (ASIC) that serves as a meansfor (e.g., structure for) carrying out one or more of the operationsdescribed in conjunction with FIGS. 1-9, 44, and 45. The processingcircuit 4310 serves as one example of a means for transmitting and/or ameans for receiving. In various implementations, the processing circuit4310 may provide and/or incorporate, at least in part, the functionalityof the GN controller 250 of FIG. 2.

According to at least one example of the apparatus 4300, the processingcircuit 4310 may include one or more of a circuit/module for identifying4320, a circuit/module for determining whether to send 4322, acircuit/module for sending 4324, a circuit/module for receiving 4326, acircuit/module for generating 4328, a circuit/module determiningmovement 4330, or a circuit/module for determining how many entries tosend 4332. In various implementations, the circuit/module foridentifying 4320, the circuit/module for determining whether to send4322, the circuit/module for sending 4324, the circuit/module forreceiving 4326, the circuit/module for generating 4328, thecircuit/module determining movement 4330, or the circuit/module fordetermining how many entries to send 4332 may provide and/orincorporate, at least in part, the functionality of the GN controller250 of FIG. 2.

As mentioned above, programming stored by the storage medium 4304, whenexecuted by the processing circuit 4310, causes the processing circuit4310 to perform one or more of the various functions and/or processoperations described herein. For example, the programming may cause theprocessing circuit 4310 to perform one or more of the various functions,steps, and/or processes described herein with respect to FIGS. 1-9, 44,and 45 in various implementations. As shown in FIG. 43, the storagemedium 4304 may include one or more of code for identifying 4340, codefor determining whether to send 4342, code for sending 4344, code forreceiving 4346, code for generating 4348, code for determining movement4350, or code for determining how many entries to send 4352. In variousimplementations, the code for identifying 4340, the code for determiningwhether to send 4342, the code for sending 4344, the code for receiving4346, the code for generating 4348, the code for determining movement4350, or the code for determining how many entries to send 4352 may beexecuted or otherwise used to provide the functionality described hereinfor the circuit/module for identifying 4320, the circuit/module fordetermining whether to send 4322, the circuit/module for sending 4324,the circuit/module for receiving 4326, the circuit/module for generating4328, the circuit/module determining movement 4330, or thecircuit/module for determining how many entries to send 4332.

The circuit/module for identifying 4320 may include circuitry and/orprogramming (e.g., code for identifying 4340 stored on the storagemedium 4604) adapted to perform several functions relating to, forexample, identifying information associated with at least one handoffentry. In some aspects, the circuit/module for identifying 4320 (e.g., ameans for identifying) may correspond to, for example, a processingcircuit.

In some implementations, the circuit/module for identifying 4320identifies a time of validity associated with a set of handoff entries.For example, the circuit/module for identifying 4320 may identify a timeof validity for an idle mode handoff table (e.g., Table 1). To this end,the circuit/module for identifying 4320 may acquires time informationfrom the memory device 4308, the circuit/module for receiving 4326, orsome other component of the apparatus 4300. In some scenarios, theidentification of the time of validity may include receiving anindication of the time of validity (e.g., from another apparatus such asa UT). In some scenarios, the identification of the time of validity mayinclude receiving an indication of a time associated with a particularentry (e.g., a last entry) of a set of handoff entries. In some cases,the circuit/module for identifying 4320 processes the acquiredinformation to determine a time of validity associated with the set ofhandoff entries. For example, the circuit/module for identifying 4320may identify the handoff time associated with the last entry in an idlemode handoff table. In any of these scenarios, the circuit/module foridentifying 4320 thereby generates an indication of the time of validityand sends the indication to a component of the apparatus 4300 (e.g., thecircuit/module for determining whether to send 4322, the memory device4308, or some other component).

The circuit/module for determining whether to send 4322 may includecircuitry and/or programming (e.g., code for determining whether to send4342 stored on the storage medium 4304) adapted to perform severalfunctions relating to, for example, determining whether to sendinformation. In some aspects, the circuit/module for determining whetherto send 4322 (e.g., a means for determining whether to send) maycorrespond to, for example, a processing circuit.

In some implementations, the information to be sent may include arequest for an updated set of handoff entries. In some scenarios, thecircuit/module for determining whether to send 4322 obtains informationthat is used to make a send decision (e.g., from the circuit/module foridentifying 4320, the circuit/module for determining movement 4330, thememory device 4308, or some other component). In some scenarios, thecircuit/module for determining whether to send 4322 may obtain anindication of a time of validity associated with a set of handoffentries. In this case, the circuit/module for determining whether tosend 4322 may determine whether to send a request based on whether thetime of validity indicates that the set of handoff entries should beupdated. For example, the sending of a request may be triggered if thetime of validity indicates that the handoff entries have expired or willsoon expire. In some scenarios, the circuit/module for determiningwhether to send 4322 may obtain an indication of movement of anotherapparatus (e.g., a UT). In this case, the circuit/module for determiningwhether to send 4322 may determine whether to send a request based on,for example, how fast the other apparatus is moving. In either case, thecircuit/module for determining whether to send 4322 generates anindication of the determination and outputs the indication (e.g., to thecircuit/module for sending 4324, the memory device 4308, or some othercomponent of the apparatus 4300).

The circuit/module for sending 4324 may include circuitry and/orprogramming (e.g., code for sending 4344 stored on the storage medium4304) adapted to perform several functions relating to, for example,sending (e.g., outputting or transmitting) information. In someimplementations, the circuit/module for sending 4324 may obtain anindication that triggers sending (e.g., from the circuit/module fordetermining whether to send 4322, the memory device 4308, or some othercomponent of the apparatus 4300). In some implementations, thecircuit/module for sending 4324 may obtain information to be sent (e.g.,a request message, an indication, location information, etc.) from thecircuit/module for identifying 4320, the circuit/module for determiningmovement 4330, the memory device 4308 or some other component of theapparatus 4300 and process the information (e.g., encode the informationfor transmission). In some scenarios, the circuit/module for sending4324 provides the information to another component (e.g., thetransmitter 4314, the communication interface 4302, or some othercomponent) that will send the information to another device. In somescenarios (e.g., if the circuit/module for sending 4324 includes atransmitter), the circuit/module for sending 4324 transmits theinformation directly to another device (e.g., the ultimate destination)via radio frequency signaling or some other type of signaling suitablefor the applicable communication medium.

The circuit/module for sending 4324 (e.g., a means for sending) may takevarious forms. In some aspects, the circuit/module for sending 4324 maycorrespond to, for example, a processing circuit as discussed herein. Insome aspects, the circuit/module for sending 4324 may correspond to, forexample, an interface (e.g., a bus interface, a send interface, or someother type of signal interface), a communication device, a transceiver,a transmitter, or some other similar component as discussed herein. Insome implementations, the communication interface 4302 includes thecircuit/module for sending 4324 and/or the code for sending 4344. Insome implementations, the circuit/module for sending 4324 and/or thecode for sending 4344 is configured to control the communicationinterface 4302 (e.g., a transceiver or a transmitter) to transmitinformation.

The circuit/module for receiving 4326 may include circuitry and/orprogramming (e.g., code for receiving 4346 stored on the storage medium4304) adapted to perform several functions relating to for example,receiving information. The information may include, without limitation,an indication, location information, etc. In some scenarios, thecircuit/module for receiving 4326 may obtain information (e.g., from thecommunication interface 4302, the memory device, or some other componentof the apparatus 4300) and process (e.g., decode) the information. Insome scenarios (e.g., if the circuit/module for receiving 4326 is orincludes an RF receiver), the circuit/module for receiving 4326 mayreceive information directly from a device that transmitted theinformation. In either case, the circuit/module for receiving 4326 mayoutput the obtained information to another component of the apparatus4300 (e.g., the circuit/module for generating 4328, the memory device4308, or some other component).

The circuit/module for receiving 4326 (e.g., a means for receiving) maytake various forms. In some aspects, the circuit/module for receiving4326 may correspond to, for example, an interface (e.g., a businterface, a send/receive interface, or some other type of signalinterface), a communication device, a transceiver, a receiver, or someother similar component as discussed herein. In some implementations,the communication interface 4302 includes the circuit/module forreceiving 4326 and/or the code for receiving 4338. In someimplementations, the circuit/module for receiving 4326 and/or the codefor receiving 4338 is configured to control the communication interface4302 (e.g., a transceiver or a receiver) to receive information.

The circuit/module for generating 4328 may include circuitry and/orprogramming (e.g., code for generating 4348 stored on the storage medium4304) adapted to perform several functions relating to, for example,generating a set of handoff entries. In some aspects, the circuit/modulefor generating 4328 (e.g., a means for generating) may correspond to,for example, a processing circuit.

In some implementations, the circuit/module for generating 4328generates a set of handoff entries based on location information foranother apparatus (e.g., a UT). To this end, the circuit/module forgenerating 4328 may obtain this location information from thecircuit/module for receiving 4326, the communication interface 4302, thememory device, or some other component of the apparatus 4300. Thecircuit/module for generating 4328 may thereby create an updated set ofhandoff entries (e.g., Table 1) based on satellite ephemeris informationand the location information. In some scenarios, the circuit/module forgenerating 4328 receives an indication of the number of handoff entriesto send (e.g., from the circuit/module for determining how many entriesto send 4332). The circuit/module for generating 4328 then outputs thisinformation (e.g., to the circuit/module for sending 4324, the memorydevice 4308, or some other component of the apparatus 4300).

The circuit/module for determining movement 4330 may include circuitryand/or programming (e.g., code for determining movement 4350 stored onthe storage medium 4304) adapted to perform several functions relatingto, for example, determining movement of an apparatus. In some aspects,the circuit/module for determining movement 4330 (e.g., a means fordetermining movement) may correspond to, for example, a processingcircuit.

In some scenarios, the circuit/module for determining movement 4330generates an indication of movement of another apparatus (e.g., a UT)based on location information for the other apparatus. To this end, thecircuit/module for determining movement 4330 may obtain this locationinformation from the circuit/module for receiving 4326, thecommunication interface 4302, the memory device, or some other componentof the apparatus 4300. The circuit/module for determining movement 4330may thereby process this obtained information to generate the indicationof movement (e.g., by generating an indication of speed or a vectorindicative of the movement). The circuit/module for determining movement4330 then outputs the indication (e.g., to the circuit/module fordetermining whether to send 4324, the memory device 4308, or some othercomponent of the apparatus 4300).

The circuit/module for determining how many entries to send 4332 mayinclude circuitry and/or programming (e.g., code for determining howmany entries to send 4352 stored on the storage medium 4304) adapted toperform several functions relating to, for example, determining how manyupdated handoff entries should be sent to another apparatus. In someaspects, the circuit/module for determining how many entries to send4332 (e.g., a means for determining how many entries to send) maycorrespond to, for example, a processing circuit.

In some scenarios, the circuit/module for determining how many entriesto send 4332 determines the number of entries based on movement of theother apparatus. To this end, the circuit/module for determining howmany entries to send 4332 may obtain movement information from thecircuit/module for determining movement 4330, the memory device, or someother component of the apparatus 4300. The circuit/module fordetermining how many entries to send 4332 may thereby process thisobtained information to determine how many entries to send. For example,as discussed herein, fewer entries may be sent to a relatively fastmoving UT than are sent to a relatively slow moving or stationary UT.Thus, in some aspects, the determination of the number of entries may bebased on at least one movement threshold, a mapping of movement tonumber of entries, or other decision criteria. The circuit/module fordetermining how many entries to send 4332 then outputs an indication ofthe number of entries to send (e.g., to the circuit/module forgenerating 4328, the memory device 4308, or some other component of theapparatus 4300).

Fourth Example Process

FIG. 44 illustrates a process 4400 for communication in accordance withsome aspects of the disclosure. The process 4400 may take place within aprocessing circuit (e.g., the processing circuit 4310 of FIG. 43), whichmay be located in a GN or some other suitable apparatus. Of course, invarious aspects within the scope of the disclosure, the process 4400 maybe implemented by any suitable apparatus capable of supportingcommunication-related operations.

At block 4402, an apparatus (e.g., a GN) identifies a time of validityassociated with a set of handoff entries. In some aspects, the set ofhandoff entries may identify a set of satellites for handoff of anotherapparatus (e.g., a UT). In some aspects, the time of validity mayindicate a duration of time that the set of handoff entries is valid.

The identification of the time of validity may take different forms indifferent implementations. In some aspects, the identification of thetime of validity may include receiving an indication of the time ofvalidity. In some aspects, the identification of the time of validitymay include receiving an indication of a time associated with aparticular entry of the set of handoff entries; and determining the timeof validity based on the received indication. In some aspects, theidentification of the time of validity may include determining a timeassociated with a last valid entry in the set of handoff entries.

The set of handoff entries may take different forms in differentimplementations. In some aspects, the set of handoff entries may includean idle mode handoff table. In some aspects, the set of handoff entriesmay identify at least one satellite for an idle mode operation of theother apparatus. In some aspects, the set of handoff entries mayidentify times at which the apparatus when in idle mode is to handoff toeach satellite of the set of satellites. In some aspects, the set ofhandoff entries may include, for each satellite, a time for theapparatus when in idle mode to handoff to the satellite. In someaspects, the set of handoff entries may include a last set of handoffentries sent by the apparatus to the other apparatus.

At block 4404, the apparatus determines, based on the identified time ofvalidity of block 4402, whether to send an updated set of handoffentries.

At block 4406, the apparatus sends the updated set of handoff entries ifthe determination is to send the updated set of handoff entries.

In some aspects, an apparatus may perform any of the operationsdiscussed above for FIG. 44, or any combination thereof.

Fifth Example Process

FIG. 45 illustrates a process 4500 for communication in accordance withsome aspects of the disclosure. One or more aspects of the process 4500may be used in conjunction with (e.g., in addition to or as part of) theprocess 4400 of FIG. 44. The process 4500 may take place within aprocessing circuit (e.g., the processing circuit 4310 of FIG. 43), whichmay be located in a GN or some other suitable apparatus. Of course, invarious aspects within the scope of the disclosure, the process 4500 maybe implemented by any suitable apparatus capable of supportingcommunication-related operations.

At optional block 4502, an apparatus (e.g., a GN) may receive anindication of a time associated with a particular entry of a set ofhandoff entries.

At optional block 4504, the apparatus may receive location informationfor an apparatus (e.g., another apparatus such as a UT).

At block 4506, the apparatus generates an updated set of handoff entries(e.g., based on the location information and/or the indication of atime).

At optional block 4508, the apparatus may determine movement of anapparatus (e.g., another apparatus such as a UT) based on the locationinformation.

At optional block 4510, the apparatus may determine whether to send theupdated set of handoff entries (e.g., based on the location informationand/or the movement of the other apparatus). In some aspects, theapparatus may determine how many updated handoff entries to send (e.g.,based on the movement of the other apparatus).

At block 4512, the apparatus sends the updated set of handoff entries.

At optional block 4514, the apparatus may send an indication of at leastone carrier frequency at which the next cell that provides coverage forthe other apparatus (e.g., a UT) will be transmitting.

In some aspects, an apparatus may perform any of the operationsdiscussed above for FIG. 45, or any combination thereof.

Third Example Apparatus

FIG. 46 illustrates a block diagram of an example hardwareimplementation of an apparatus 4600 configured to communicate accordingto one or more aspects of the disclosure. For example, the apparatus4600 could embody or be implemented within a GN or some other type ofdevice that supports satellite communication. Thus, in some aspects, theapparatus 4600 could be an example of the GN 200 or the GN 201 ofFIG. 1. In various implementations, the apparatus 4600 could embody orbe implemented within a gateway, a ground station, a vehicularcomponent, or any other electronic device having circuitry.

The apparatus 4600 includes a communication interface (e.g., at leastone transceiver) 4602, a storage medium 4604, a user interface 4606, amemory device (e.g., a memory circuit) 4608, and a processing circuit(e.g., at least one processor) 4610. In various implementations, theuser interface 4606 may include one or more of: a keypad, a display, aspeaker, a microphone, a touchscreen display, of some other circuitryfor receiving an input from or sending an output to a user.

These components can be coupled to and/or placed in electricalcommunication with one another via a signaling bus or other suitablecomponent, represented generally by the connection lines in FIG. 46. Thesignaling bus may include any number of interconnecting buses andbridges depending on the specific application of the processing circuit4610 and the overall design constraints. The signaling bus linkstogether various circuits such that each of the communication interface4602, the storage medium 4604, the user interface 4606, and the memorydevice 4608 are coupled to and/or in electrical communication with theprocessing circuit 4610. The signaling bus may also link various othercircuits (not shown) such as timing sources, peripherals, voltageregulators, and power management circuits, which are well known in theart, and therefore, will not be described any further.

The communication interface 4602 provides a means for communicating withother apparatuses over a transmission medium. In some implementations,the communication interface 4602 includes circuitry and/or programmingadapted to facilitate the communication of information bi-directionallywith respect to one or more communication devices in a network. In someimplementations, the communication interface 4602 is adapted tofacilitate wireless communication of the apparatus 4600. In theseimplementations, the communication interface 4602 may be coupled to oneor more antennas 4612 as shown in FIG. 46 for wireless communicationwithin a wireless communication system. The communication interface 4602can be configured with one or more standalone receivers and/ortransmitters, as well as one or more transceivers. In the illustratedexample, the communication interface 4602 includes a transmitter 4614and a receiver 4616. The communication interface 4602 serves as oneexample of a means for receiving and/or means transmitting.

The memory device 4608 may represent one or more memory devices. Asindicated, the memory device 4608 may maintain satellite-relatedinformation 4618 along with other information used by the apparatus4600. In some implementations, the memory device 4608 and the storagemedium 4604 are implemented as a common memory component. The memorydevice 4608 may also be used for storing data that is manipulated by theprocessing circuit 4610 or some other component of the apparatus 4600.

The storage medium 4604 may represent one or more computer-readable,machine-readable, and/or processor-readable devices for storingprogramming, such as processor executable code or instructions (e.g.,software, firmware), electronic data, databases, or other digitalinformation. The storage medium 4604 may also be used for storing datathat is manipulated by the processing circuit 4610 when executingprogramming. The storage medium 4604 may be any available media that canbe accessed by a general purpose or special purpose processor, includingportable or fixed storage devices, optical storage devices, and variousother mediums capable of storing, containing or carrying programming.

By way of example and not limitation, the storage medium 4604 mayinclude a magnetic storage device (e.g., hard disk, floppy disk,magnetic strip), an optical disk (e.g., a compact disc (CD) or a digitalversatile disc (DVD)), a smart card, a flash memory device (e.g., acard, a stick, or a key drive), a random access memory (RAM), a readonly memory (ROM), a programmable ROM (PROM), an erasable PROM (EPROM),an electrically erasable PROM (EEPROM), a register, a removable disk,and any other suitable medium for storing software and/or instructionsthat may be accessed and read by a computer. The storage medium 4604 maybe embodied in an article of manufacture (e.g., a computer programproduct). By way of example, a computer program product may include acomputer-readable medium in packaging materials. In view of the above,in some implementations, the storage medium 4604 may be a non-transitory(e.g., tangible) storage medium.

The storage medium 4604 may be coupled to the processing circuit 4610such that the processing circuit 4610 can read information from, andwrite information to, the storage medium 4604. That is, the storagemedium 4604 can be coupled to the processing circuit 4610 so that thestorage medium 4604 is at least accessible by the processing circuit4610, including examples where at least one storage medium is integralto the processing circuit 4610 and/or examples where at least onestorage medium is separate from the processing circuit 4610 (e.g.,resident in the apparatus 4600, external to the apparatus 4600,distributed across multiple entities, etc.).

Programming stored by the storage medium 4604, when executed by theprocessing circuit 4610, causes the processing circuit 4610 to performone or more of the various functions and/or process operations describedherein. For example, the storage medium 4604 may include operationsconfigured for regulating operations at one or more hardware blocks ofthe processing circuit 4610, as well as to utilize the communicationinterface 4602 for wireless communication utilizing their respectivecommunication protocols.

The processing circuit 4610 is generally adapted for processing,including the execution of such programming stored on the storage medium4604. As used herein, the terms “code” or “programming” shall beconstrued broadly to include without limitation instructions,instruction sets, data, code, code segments, program code, programs,programming, subprograms, software modules, applications, softwareapplications, software packages, routines, subroutines, objects,executables, threads of execution, procedures, functions, etc., whetherreferred to as software, firmware, middleware, microcode, hardwaredescription language, or otherwise.

The processing circuit 4610 is arranged to obtain, process and/or senddata, control data access and storage, issue commands, and control otherdesired operations. The processing circuit 4610 may include circuitryconfigured to implement desired programming provided by appropriatemedia in at least one example. For example, the processing circuit 4610may be implemented as one or more processors, one or more controllers,and/or other structure configured to execute executable programming.Examples of the processing circuit 4610 may include a general purposeprocessor, a digital signal processor (DSP), an application specificintegrated circuit (ASIC), a field programmable gate array (FPGA) orother programmable logic component, discrete gate or transistor logic,discrete hardware components, or any combination thereof designed toperform the functions described herein. A general purpose processor mayinclude a microprocessor, as well as any conventional processor,controller, microcontroller, or state machine. The processing circuit4610 may also be implemented as a combination of computing components,such as a combination of a DSP and a microprocessor, a number ofmicroprocessors, one or more microprocessors in conjunction with a DSPcore, an ASIC and a microprocessor, or any other number of varyingconfigurations. These examples of the processing circuit 4610 are forillustration and other suitable configurations within the scope of thedisclosure are also contemplated.

According to one or more aspects of the disclosure, the processingcircuit 4610 may be adapted to perform any or all of the features,processes, functions, operations and/or routines for any or all of theapparatuses described herein. For example, the processing circuit 4610may be configured to perform one or more of the steps, functions, and/orprocesses described with respect to FIGS. 11, 12, 15-24, 27, 29, 31-33,35, 37, 47, and 48. As used herein, the term “adapted” in relation tothe processing circuit 4610 may refer to the processing circuit 4610being one or more of configured, employed, implemented, and/orprogrammed to perform a particular process, function, operation and/orroutine according to various features described herein.

The processing circuit 4610 may be a specialized processor, such as anapplication specific integrated circuit (ASIC) that serves as a meansfor (e.g., structure for) carrying out one or more of the operationsdescribed in conjunction with FIGS. 11, 12, 15-24, 27, 29, 31-33, 35,37, 47, and 48. The processing circuit 4610 serves as one example of ameans for transmitting and/or a means for receiving. In someimplementations, the processing circuit 4610 incorporates thefunctionality of the GN controller 250 of FIG. 2.

According to at least one example of the apparatus 4600, the processingcircuit 4610 may include one or more of a circuit/module for generating4620, a circuit/module for sending 4622, a circuit/module for performinghandoffs 4624, a circuit/module for receiving 4626, a circuit/module fordetermining whether to modify 4628, a circuit/module for selecting 4630,a circuit/module for determining a time 4632, a circuit/module fortransferring 4634, a circuit/module for determining a measurement gap4636, or a circuit/module for determining that a measurement gap is notneeded 4638. In various implementations, the circuit/module forgenerating 4620, the circuit/module for sending 4622, the circuit/modulefor performing handoffs 4624, the circuit/module for receiving 4626, thecircuit/module for determining whether to modify 4628, thecircuit/module for selecting 4630, the circuit/module for determining atime 4632, the circuit/module for transferring 4634, the circuit/modulefor determining a measurement gap 4636, and the circuit/module fordetermining that a measurement gap is not needed 4638 may correspond, atleast in part, to the GN controller 250 of FIG. 2.

The circuit/module for generating 4620 may include circuitry and/orprogramming (e.g., code for generating 4640 stored on the storage medium4604) adapted to perform several functions relating to, for example,generating satellite and cell transition information that specifies atime to start and a time to terminate communication with a particularcell of a particular satellite. In some implementations, thecircuit/module for generating 4620 calculates the information (e.g., thedata for Table 1) based on satellite ephemeris data and user terminallocation data. To this end, the circuit/module for generating 4620collects this data, processes the data to generate the information andsends the information to a component of the apparatus 4600 (e.g., thememory device 4608). For example, for a given location of a userterminal, the circuit/module for generating 4620 can determine when aparticular cell of a particular satellite will provide coverage for theuser terminal based on the location of the satellite and thedirectionality and coverage of the cells of the satellite over time.

The circuit/module for sending 4622 may include circuitry and/orprogramming (e.g., code for sending 4642 stored on the storage medium4604) adapted to perform several functions relating to, for example,sending information (e.g., data) to another apparatus. Initially, thecircuit/module for sending 4622 obtains the information to be sent(e.g., from the memory device 4608, the circuit/module for generating4620, or some other component). In various implementations, theinformation to be sent may include satellite and cell transitioninformation to be sent to a user terminal. In various implementations,the information to be sent may include information indicative of ameasurement gap. The circuit/module for sending 4622 may then format theinformation for sending (e.g., in a message, according to a protocol,etc.). The circuit/module for sending 4622 then causes the informationto be sent via a wireless communication medium (e.g., via satellitesignaling). To this end, the circuit/module for sending 4622 may sendthe data to the communication interface 4602 (e.g., a digital subsystemor an RF subsystem) or some other component for transmission. In someimplementations, the communication interface 4602 includes thecircuit/module for sending 4622 and/or the code for sending 4642.

The circuit/module for performing a handoff 4624 may include circuitryand/or programming (e.g., code for performing a handoff 4644 stored onthe storage medium 4604) adapted to perform several functions relatingto, for example, performing handoffs for a user terminal to differentcells and at least one satellite. In some implementations, thecircuit/module for performing a handoff 4624 identifies the targetsatellite and/or the target cell based on the satellite and celltransition information (e.g., Table 1). To this end, the circuit/modulefor performing a handoff 4624 collects this information, processes theinformation to identify the target, and reconfigures its communicationparameters to cause communication with the user terminal to be conductedvia the target. For example, for a given location of a user terminal,the circuit/module for performing a handoff 4624 can determine whether aparticular cell of a particular satellite would provide sufficientcoverage for the user terminal based on the location of the satelliteand the directionality and coverage of the cells of the satellite overtime. If the satellite/cell would provide sufficient coverage, thecircuit/module for performing a handoff 4624 can designate thatsatellite/cell as the target for the handoff and commence handoffsignaling accordingly.

The circuit/module for receiving 4626 may include circuitry and/orprogramming (e.g., code for receiving 4646 stored on the storage medium4604) adapted to perform several functions relating to, for example,receiving information (e.g., data) from another apparatus. In variousimplementations, the information to be received may include ameasurement message from a user terminal. In various implementations,the information to be received may include capability information from auser terminal. In various implementations, the information to bereceived may include a message from a user terminal. Initially, thecircuit/module for receiving 4626 obtains received information. Forexample, the circuit/module for receiving 4626 may obtain thisinformation from a component of the apparatus 4600 (e.g., thecommunication interface 4602 (e.g., a digital subsystem or an RFsubsystem), the memory device 4608, or some other component) or directlyfrom a device (e.g., a satellite) that relayed the information from theuser terminal. In some implementations, the circuit/module for receiving4626 identifies a memory location of a value in the memory device 4608and invokes a read of that location. In some implementations, thecircuit/module for receiving 4626 processes (e.g., decodes) the receivedinformation. The circuit/module for receiving 4626 outputs the receivedinformation (e.g., stores the received information in the memory device4608 or sends the information to another component of the apparatus4600). In some implementations, the communication interface 4602includes the circuit/module for receiving 4626 and/or the code forreceiving 4642.

The circuit/module for determining whether to modify 4628 may includecircuitry and/or programming (e.g., code for determining whether tomodify 4648 stored on the storage medium 4604) adapted to performseveral functions relating to, for example, determining whether tomodify the satellite and cell transition information. In someimplementations, the circuit/module for determining whether to modify4628 makes this determination based on the received measurement message.To this end, the circuit/module for determining whether to modify 4628collects this measurement message information (e.g., from thecircuit/module for receiving 4626, the memory device 4608, or some othercomponent of the apparatus 4600). The circuit/module for determiningwhether to modify 4628 may then process the information to determinewhether the current timing parameters need to be changed (e.g., due topoor RF conditions or improved RF conditions). For example, thecircuit/module for determining whether to modify 4628 may compare signalquality information contained in a measurement message with one or moresignal quality thresholds. Finally, the circuit/module for determiningwhether to modify 4628 generates an indication of this determination(e.g., indicative of advancement of a handoff or delay of a handoff).

The circuit/module for selecting 4630 may include circuitry and/orprogramming (e.g., code for selecting 4650 stored on the storage medium4604) adapted to perform several functions relating to, for example,selecting a handoff procedure for a user terminal. In someimplementations, the circuit/module for selecting 4630 makes thisdetermination based on capability information received from the userterminal. To this end, the circuit/module for selecting 4630 collectsthis capability information, processes the information to identify ahandoff procedure, and generates an indication of this determination.For example, the selection of the handoff procedure may involvedetermining whether the user terminal is dual sense capable, andenabling or disabling monitoring for a measurement message from the userterminal based on whether the user terminal is dual sense capable. Thus,in some implementations, the circuit/module for selecting 4630 acquiresconfiguration information about the user terminal (e.g., from the memorydevice 4608, from the receiver 4616, or from some other component),checks this information to identify the capability of the user terminalto select a supported handoff procedure, and generates an indication ofthis determination (e.g., that is sent to the memory device 4608, thecircuit/module for performing a handoff 4624, or some other component).

The circuit/module for determining a time 4632 may include circuitryand/or programming (e.g., code for determining a time 4652 stored on thestorage medium 4604) adapted to perform several functions relating to,for example, determining a time of handoff of a user terminal. In someimplementations, the circuit/module for determining a time 4632 makesthis determination based on the satellite and cell transitioninformation (e.g., Table 1). To this end, the circuit/module fordetermining a time 4632 acquires this information (e.g., from thecircuit/module for receiving 4626, the memory device 4608, or some othercomponent of the apparatus 4600). The circuit/module for a time 4632 maythen process the information to determine the time (e.g., the framenumber) for the next handoff of the user terminal. For example, thecircuit/module for a time 4632 may compare a current time indication(e.g., a frame number) with the timing indications in Table 1. Thecircuit/module for determining a time 4632 generates an indication ofthis determination (e.g., indicative of the time of handoff) and sendsthe indication to a component of the apparatus 4600 (e.g., thecircuit/module for transferring 4634, the memory device 4608, or someother component).

The circuit/module for transferring 4634 may include circuitry and/orprogramming (e.g., code for transferring 4654 stored on the storagemedium 4604) adapted to perform several functions relating to, forexample, transferring user queues prior to handoff. Initially, thecircuit/module for transferring 4634 receives an indication of a time ofhandoff (e.g., from the memory device 4608, the circuit/module fordetermining a time 4632, or some other component). Next, prior to thetime of handoff, the circuit/module for transferring 4634 obtains queueinformation to be sent (e.g., from the memory device 4608, or some othercomponent). In various implementations, this information may be sent toanother GN. The circuit/module for transferring 4634 may then format thequeue information for sending (e.g., in a message, according to aprotocol, etc.). The circuit/module for transferring 4634 then causesthe queue information to be sent via an appropriate communication medium(e.g., via the infrastructure 106 of FIG. 1). To this end, thecircuit/module for transferring 4634 may send the data to thecommunication interface 4602 or some other component for transmission.In some implementations, the communication interface 4602 includes thecircuit/module for transferring 4634 and/or the code for transferring4654.

The circuit/module for determining a measurement gap 4636 may includecircuitry and/or programming (e.g., code for determining a measurementgap 4656 stored on the storage medium 4604) adapted to perform severalfunctions relating to, for example, determining a measurement gap formeasuring satellite signals. In some implementations, the circuit/modulefor determining a measurement gap 4636 determines that there may be asatellite pointing error that necessitates a change in a handoff time.As a result of this determination or some other trigger, thecircuit/module for determining a measurement gap 4636 generates anindication of a measurement gap to be used by a UT (e.g., a measurementgap pattern indicative of times when the GN is not transmitting to theUT). The circuit/module for determining a measurement gap 4636 thensends the indication to a component of the apparatus 4600 (e.g., thecircuit/module for sending 4622, the memory device 4608, or some othercomponent).

The circuit/module for determining that a measurement gap is not needed4638 may include circuitry and/or programming (e.g., code fordetermining that a measurement gap is not needed 4658 stored on thestorage medium 4604) adapted to perform several functions relating to,for example, determining that a measurement gap is not needed formeasuring satellite signals. In some implementations, the circuit/modulefor determining that a measurement gap is not needed 4638 obtainsinformation regarding the status of one or more satellites. Based onthis information, the circuit/module for determining that a measurementgap is not needed 4638 determines that there is no satellite pointingerror that would necessitate a change in a handoff time. As a result ofthis determination or some other trigger, the circuit/module fordetermining that a measurement gap is not needed 4638 generates anindication of this determination and sends the indication to a componentof the apparatus 4600 (e.g., the circuit/module for generating 4620, thememory device 4608, or some other component).

As mentioned above, programming stored by the storage medium 4604, whenexecuted by the processing circuit 4610, causes the processing circuit4610 to perform one or more of the various functions and/or processoperations described herein. For example, the programming, when executedby the processing circuit 4610, may cause the processing circuit 4610 toperform one or more of the various functions, steps, and/or processesdescribed herein with respect to FIGS. 11, 12, 15-24, 27, 29, 31-33, 35,37, 47, and 48 in various implementations. As shown in FIG. 46, thestorage medium 4604 may include one or more of the code for generating4640, the code for sending 4642, the code for performing handoffs 4644,the code for receiving 4646, the code for determining whether to modify4648, the code for selecting 4650, the code for determining a time 4652,the code for transferring 4654, the code for determining a measurementgap 4656, or the code for determining that a measurement gap is notneeded 4658.

Sixth Example Process

FIG. 47 illustrates a process 4700 for communication in accordance withsome aspects of the disclosure. The process 4700 may take place within aprocessing circuit (e.g., the processing circuit 4610 of FIG. 46), whichmay be located in a GN or some other suitable apparatus. In someimplementations, the process 4700 may be performed by a GN for at leastone non-geosynchronous satellite. In some implementations, the process4700 represents operations performed by the GN controller 250 of FIG. 2.Of course, in various aspects within the scope of the disclosure, theprocess 4700 may be implemented by any suitable apparatus capable ofsupporting communication operations.

At block 4702, an apparatus (e.g., a GN) generates satellite handoffinformation that specifies a handoff time for a particular cell of aparticular satellite. In some aspects, the operations of block 4702 maycorrespond to the operations of block 2406 of FIG. 24.

In some aspects, the generation of the satellite handoff information maybe based on at least one of: capabilities information for a userterminal or location information for a user terminal. In some aspects,the capabilities information may indicate at least one of: whether theuser terminal can sense multiple beams or whether the user terminal cansense multiple satellites. In some aspects, the capabilities informationmay indicate at least one of: an inter-beam tune time for the userterminal or an inter-satellite tune time for the user terminal. In someaspects, the location information may include at least one of: a currentlocation for the user terminal or a motion vector for the user terminal.

In some aspects, the generation of the satellite handoff information maybe based on at least one of: ephemeris information, a restriction due toan incumbent system, or a satellite pointing error. In some aspects, thegeneration of the satellite handoff information may be triggered basedon at least one of: handoff of the user terminal to a differentsatellite or receipt of a measurement message from the user terminal.

In some implementations, the circuit/module for generating 4620 of FIG.46 performs the operations of block 4702. In some implementations, thecode for generating 4640 of FIG. 46 is executed to perform theoperations of block 4702.

At block 4704, the apparatus sends the satellite handoff information toa user terminal. In some aspects, this information is sent via asatellite. In some aspects, the operations of block 4704 may correspondto the operations of block 2408 of FIG. 24.

The satellite handoff information may take various forms as taughtherein. In some aspects, the satellite handoff information may include atable that includes a handoff activation time. In some aspects, thesatellite handoff information may include at least one tune-away time.In some aspects, the handoff information may be for at least one futurehandoff (e.g., the next handoff, a later handoff, or some other handoffthat will occur in the future). In some aspects, the handoff informationmay be for the next beam handoff and for at least one future satellitehandoff (e.g., for the next two handoffs that will occur, the nexthandoff and some other subsequent handoff, etc.).

In some implementations, the circuit/module for sending 4622 of FIG. 46performs the operations of block 4704. In some implementations, the codefor sending 4642 of FIG. 46 is executed to perform the operations ofblock 4704.

In some aspects, the process 4700 may further include performinghandoffs for the user terminal to different beams and at least onesatellite based on the satellite handoff information. The handoffs mayinvolve a change of at least one of: a satellite access network (SAN) ora GN antenna. The handoffs may involve a change of at least one of: asatellite beam or a forward service link (FSL) frequency. In someaspects, these operations may correspond to the operations of block 2410of FIG. 24. In some implementations, the circuit/module for performing ahandoff 4624 of FIG. 46 performs these operations. In someimplementations, the code for performing a handoff 4644 of FIG. 46 isexecuted to perform these operations.

In some aspects, the process 4700 may further include receiving ameasurement message from the user terminal, and determining, based onthe measurement message, whether to modify the satellite handoffinformation. The modification of the satellite handoff information mayinclude advancing handoff timing or delaying handoff timing. In someaspects, these operations may correspond to the operations of blocks3102 and 3104 of FIG. 31. In some implementations, the circuit/modulefor receiving 4626 of FIG. 46 performs the receiving operations. In someimplementations, the code for receiving 4646 of FIG. 46 is executed toperform the receiving operations. In some implementations, thecircuit/module for determining whether to modify 4628 of FIG. 46performs the determining operations. In some implementations, the codefor determining whether to modify 4648 of FIG. 46 is executed to performthe determining operations.

In some aspects, the process 4700 may further include determining ameasurement gap for measuring satellite signals, and sending informationindicative of the measurement gap to the user terminal, wherein themeasurement message includes an indication of a measurement of signalsfrom at least one satellite conducted during the measurement gap. Insome aspects, these operations may correspond to the operations ofblocks 3506 and 3508 of FIG. 35. In some implementations, thecircuit/module for determining a measurement gap 4636 of FIG. 46performs the determining operations. In some implementations, the codefor determining a measurement gap 4656 of FIG. 46 is executed to performthe determining operations. In some implementations, the circuit/modulefor sending 4622 of FIG. 46 performs the sending operations. In someimplementations, the code for sending 4642 of FIG. 46 is executed toperform the sending operations.

In some aspects, the process 4700 may further include receivingcapability information from the user terminal, and selecting a handoffprocedure for the user terminal based on the received capabilityinformation. the capability information may indicate whether the userterminal is dual sense capable. The selection of the handoff proceduremay include enabling or disabling monitoring for a measurement messagefrom the user terminal based on whether the user terminal is dual sensecapable. In some aspects, these operations may correspond to theoperations of blocks 2702 and 2706 of FIG. 27. In some implementations,the circuit/module for receiving 4626 of FIG. 46 performs the receivingoperations. In some implementations, the code for receiving 4646 of FIG.46 is executed to perform the receiving operations. In someimplementations, the circuit/module for selecting 4630 of FIG. 46performs the selecting operations. In some implementations, the code forselecting 4650 of FIG. 46 is executed to perform the selectingoperations.

In some aspects, the process 4700 may further include determining a timeof a handoff of the user terminal, and transferring at least one userqueue prior to the handoff. In some aspects, these operations maycorrespond to the operations of blocks 3702 and 3704 of FIG. 37. In someimplementations, the circuit/module for determining a time 4632 of FIG.46 performs the determining operations. In some implementations, thecode for determining a time 4652 of FIG. 46 is executed to perform thedetermining operations. In some implementations, the circuit/module fortransferring 4634 of FIG. 46 performs the transferring operations. Insome implementations, the code for transferring 4654 of FIG. 46 isexecuted to perform the transferring operations.

In some aspects, the process 4700 may further include receiving, fromthe user terminal, a message comprising at least one of: user terminalpaging area information or user terminal location information. In someaspects, these operations may correspond to the operations of block 2902of FIG. 29. In some implementations, the circuit/module for receiving4626 of FIG. 46 performs these operations. In some implementations, thecode for receiving 4646 of FIG. 46 is executed to perform theseoperations.

In some aspects, the process 4700 may further include determining that ameasurement gap is not needed for measuring satellite signals, wherein,as a result of the determination, the generation of the satellitehandoff information involves not including a tune-away time in thesatellite handoff information. In some aspects, these operations maycorrespond to the operations of blocks 3502 and 3504 of FIG. 35. In someimplementations, the circuit/module for determining that a measurementgap is not needed 4638 of FIG. 46 performs these operations. In someimplementations, the code for determining that a measurement gap is notneeded 4658 of FIG. 46 is executed to perform these operations.

Seventh Example Process

FIG. 48 illustrates a process 4800 for communication in accordance withsome aspects of the disclosure. The process 4800 may take place within aprocessing circuit (e.g., the processing circuit 4610 of FIG. 46), whichmay be located in a GN or some other suitable apparatus. In someimplementations, the process 4800 may be performed by a GN for at leastone non-geosynchronous satellite. In some implementations, the process4800 represents operations performed by the GN controller 250 of FIG. 2.Of course, in various aspects within the scope of the disclosure, theprocess 4800 may be implemented by any suitable apparatus capable ofsupporting communication operations.

At block 4802, an apparatus (e.g., a GN) generates satellite and celltransition information that specifies a time to start and a time toterminate communication with a particular cell of a particularsatellite. In some aspects, the operations of block 4802 may correspondto the operations of block 2406 of FIG. 24.

In some aspects, the satellite and cell transition information isgenerated based on at least one of: capabilities information for theuser terminal, location information for the user terminal, ephemerisinformation, or a restriction due to an incumbent system. In someaspects, the capabilities information indicates at least one of: whetherthe user terminal can sense multiple cells, whether the user terminalcan sense multiple satellites, an inter-cell tune time for the userterminal, or an inter-satellite tune time for the user terminal. In someaspects, the location information includes a current location for theuser terminal or a motion vector for the user terminal.

In some aspects, the generation of the satellite and cell transitioninformation is triggered based on at least one of: handoff of the userterminal to a different satellite, or receipt of a measurement messagefrom the user terminal.

In some implementations, the circuit/module for generating 4620 of FIG.46 performs the operations of block 4802. In some implementations, thecode for generating 4640 of FIG. 46 is executed to perform theoperations of block 4802.

At block 4804, the apparatus sends the satellite and cell transitioninformation to a user terminal. In some aspects, this information issent via a satellite. In some aspects, the operations of block 4804 maycorrespond to the operations of block 2408 of FIG. 24.

In some implementations, the circuit/module for sending 4622 of FIG. 46performs the operations of block 4804. In some implementations, the codefor sending 4642 of FIG. 46 is executed to perform the operations ofblock 4804.

In some aspects, the process 4800 further includes performing handoffsfor the user terminal to different cells and at least one satellitebased on the satellite and cell transition information. In some aspects,these operations may correspond to the operations of block 2410 of FIG.24. In some implementations, the circuit/module for performing a handoff4624 of FIG. 46 performs these operations. In some implementations, thecode for performing a handoff 4644 of FIG. 46 is executed to performthese operations.

In some aspects, the process 4800 further includes receiving ameasurement message from the user terminal; and determining, based onthe measurement message, whether to modify the satellite and celltransition information. In some aspects, the modification of thesatellite and cell transition information includes advancing a handoffor delaying a handoff. In some aspects, these operations may correspondto the operations of blocks 3102 and 3104 of FIG. 31. In someimplementations, the circuit/module for receiving 4626 and/or thecircuit/module for determining whether to modify 4628 of FIG. 46performs these operations. In some implementations, the code forreceiving 4646 and/or the code for determining whether to modify 4648 ofFIG. 46 is executed to perform these operations.

In some aspects, the process 4800 further includes selecting a handoffprocedure for the user terminal based on capability information receivedfrom the user terminal. In some aspects, the selection of the handoffprocedure includes enabling or disabling monitoring for a measurementmessage from the user terminal based on whether the user terminal isdual sense capable. In some aspects, these operations may correspond tothe operations of block 2706 of FIG. 27. In some implementations, thecircuit/module for selecting 4630 of FIG. 46 performs these operations.In some implementations, the code for selecting 4650 of FIG. 46 isexecuted to perform these operations.

In some aspects, the process 4800 further includes determining a time ofa handoff of the user terminal and transferring user queues prior to thehandoff. In some implementations, the circuit/module for determining atime 4632 and/or the circuit/module for transferring 4634 of FIG. 46performs these operations. In some implementations, the code fordetermining a time 4652 and/or the code for transferring 4654 of FIG. 46is executed to perform these operations.

Fourth Example Apparatus

FIG. 49 illustrates a block diagram of an example hardwareimplementation of another apparatus 4900 configured to communicateaccording to one or more aspects of the disclosure. For example, theapparatus 4900 could embody or be implemented within a UT or some othertype of device that supports wireless communication. Thus, in someaspects, the apparatus 4900 could be an example of the UT 400 or the UT401 of FIG. 1. In various implementations, the apparatus 4900 couldembody or be implemented within a mobile phone, a smart phone, a tablet,a portable computer, a server, a personal computer, a sensor, anentertainment device, a vehicular component, medical devices, or anyother electronic device having circuitry.

The apparatus 4900 includes a communication interface (e.g., at leastone transceiver) 4902, a storage medium 4904, a user interface 4906, amemory device 4908 (e.g., storing satellite-related information 4918),and a processing circuit (e.g., at least one processor) 4910. In variousimplementations, the user interface 4906 may include one or more of: akeypad, a display, a speaker, a microphone, a touchscreen display, ofsome other circuitry for receiving an input from or sending an output toa user. The communication interface 4902 may be coupled to one or moreantennas 4912, and may include a transmitter 4914 and a receiver 4916.In general, the components of FIG. 49 may be similar to correspondingcomponents of the apparatus 4600 of FIG. 46.

According to one or more aspects of the disclosure, the processingcircuit 4910 may be adapted to perform any or all of the features,processes, functions, operations and/or routines for any or all of theapparatuses described herein. For example, the processing circuit 4910may be configured to perform one or more of the steps, functions, and/orprocesses described with respect to FIGS. 11, 12, 15-23, 25, 26, 28, 30,32-34, 36, 38, 50, and 51. As used herein, the term “adapted” inrelation to the processing circuit 4910 may refer to the processingcircuit 4910 being one or more of configured, employed, implemented,and/or programmed to perform a particular process, function, operationand/or routine according to various features described herein.

The processing circuit 4910 may be a specialized processor, such as anapplication specific integrated circuit (ASIC) that serves as a meansfor (e.g., structure for) carrying out one or more of the operationsdescribed in conjunction with FIGS. 11, 12, 15-23, 25, 26, 28, 30,32-34, 36, 38, 50, and 51. The processing circuit 4910 serves as oneexample of a means for transmitting and/or a means for receiving. Invarious implementations, the processing circuit 4910 may incorporate thefunctionality of the control processor 420 of FIG. 4.

According to at least one example of the apparatus 4900, the processingcircuit 4910 may include one or more of a circuit/module for receiving4920, a circuit/module for performing a handoff 4922, a circuit/modulefor measuring signals 4924, a circuit/module for sending 4926, acircuit/module for determining whether to send 4928, or a circuit/modulefor performing a random access procedure 4930. In variousimplementations, the circuit/module for receiving 4920, thecircuit/module for performing a handoff 4922, the circuit/module formeasuring signals 4924, the circuit/module for sending 4926, thecircuit/module for determining whether to send 4928, and thecircuit/module for performing a random access procedure 4930 maycorrespond, at least in part, to the control processor 420 of FIG. 4.

The circuit/module for receiving 4920 may include circuitry and/orprogramming (e.g., code for receiving 4932 stored on the storage medium4904) adapted to perform several functions relating to, for example,receiving information (e.g., data) from another apparatus. In variousimplementations, the information to be received may include satelliteand cell transition information that specifies a time to start and atime to terminate communication with a particular cell of a particularsatellite. In various implementations, the information to be receivedmay include information indicative of a measurement gap. In variousimplementations, the information to be received may include a dedicatedpreamble signature. Initially, the circuit/module for receiving 4920obtains received information. For example, the circuit/module forreceiving 4920 may obtain this information from a component of theapparatus 4900 or directly from a device (e.g., a satellite) thatrelayed the information from a GN. In the former case, thecircuit/module for receiving 4920 may obtain this information from thecommunication interface 4902 (e.g., a UT transceiver as described abovefor the UT 400 of FIG. 4), the memory device 4908, or some othercomponent. In some implementations, the circuit/module for receiving4920 identifies a memory location of a value in the memory device 4908and invokes a read of that location. In some implementations, thecircuit/module for receiving 4920 processes (e.g., decodes) the receivedinformation. The circuit/module for receiving 4920 outputs the receivedinformation (e.g., sends the received information to the memory device4908, the circuit/module for performing a handoff 4922, or some othercomponent of the apparatus 4900). In some implementations, thecommunication interface 4902 includes the circuit/module for receiving4920 and/or the code for receiving 4932.

The circuit/module for performing a handoff 4922 may include circuitryand/or programming (e.g., code for performing a handoff 4934 stored onthe storage medium 4904) adapted to perform several functions relatingto, for example, performing handoff to a particular cell of a particularsatellite. In some implementations, the circuit/module for performing ahandoff 4922 identifies a particular cell of a particular satellitebased on satellite and cell transition information (e.g., Table 1). Tothis end, the circuit/module for performing a handoff 4922 collects thisinformation, processes the information to identify the satellite andcell, and reconfigures its communication parameters to causecommunication with a GN to be conducted via the identified satellite andcell. For example, at a particular point in time, the circuit/module forperforming a handoff 4922 can use the information in Table 1 todetermine whether the user terminal should switch to a differentsatellite cell. As another example, triggers may be set up atcell/satellite transitions times (e.g., frame numbers) indicated inTable 1.

The circuit/module for measuring signals 4924 may include circuitryand/or programming (e.g., code for measuring signals 4936 stored on thestorage medium 4904) adapted to perform several functions relating to,for example, receiving and processing signals from at least onesatellite. Initially, the circuit/module for measuring signals 4924receives signals. For example, the circuit/module for measuring signals4924 may obtain signal information from a component of the apparatus4900 or directly from a satellite that transmitted the signals. As anexample of the former case, the circuit/module for measuring signals4924 may obtain signal information from the communication interface 4902(e.g., a UT transceiver as described above for the UT 400 of FIG. 4),the memory device 4908 (e.g., if the received signals have beendigitized), or some other component of the apparatus 4900. Thecircuit/module for measuring signals 4924 then processes the receivedsignals (e.g., to determine at least one signal quality of the signals).Finally, the circuit/module for measuring signals 4924 generates anindication of this measurement and sends the indication to the memorydevice 4908, the circuit/module for sending 4924, or some othercomponent of the apparatus 4900. In some implementations, thecommunication interface 4902 includes the circuit/module for measuringsignals 4924 and/or the code for measuring signals 4936.

The circuit/module for sending 4926 may include circuitry and/orprogramming (e.g., code for sending 4938 stored on the storage medium4904) adapted to perform several functions relating to, for example,sending information (e.g., messages) to another apparatus. Initially,the circuit/module for sending 4926 obtains the information to be sent(e.g., from the memory device 4908, the circuit/module for measuringsignals 4924, or some other component). In various implementations, theinformation to be sent may include a measurement message based onmeasured signals, a message including user terminal capabilityinformation, or a message including user terminal location information.In various implementations, the information to be sent may include amessage including user terminal capability information. In variousimplementations, the information to be sent may include a messageincluding user terminal location information. In variousimplementations, the information to be sent may include a messageincluding user terminal paging area information. The circuit/module forsending 4926 may format the information for sending (e.g., according toa message format, according to a protocol, etc.). The circuit/module forsending 4926 then causes the information to be sent via a wirelesscommunication medium (e.g., via satellite signaling). To this end, thecircuit/module for sending 4926 may send the data to the communicationinterface 4902 (e.g., a UT transceiver as described above for the UT 400of FIG. 4) or some other component for transmission. In someimplementations, the communication interface 4902 includes thecircuit/module for sending 4926 and/or the code for sending 4938.

The circuit/module for determining whether to send 4928 may includecircuitry and/or programming (e.g., code for determining whether to send4940 stored on the storage medium 4904) adapted to perform severalfunctions relating to, for example, determining whether to send amessage. In some implementations, the information to be sent may includea measurement message that is based on measured signals. Initially, thecircuit/module for determining whether to send 4928 obtains informationthat is used to make a send decision (e.g., from the memory device 4908,the circuit/module for measuring signals 4924, or some other component).For example, the circuit/module for determining whether to send 4928 mayobtain signal quality information from the circuit/module for measuringsignals 4924. In this case, the circuit/module for determining whetherto send 4928 may determine whether the signals from a current servingsatellite and/or from a target satellite are inadequate (e.g., bycomparing the signal quality information with a signal qualitythreshold). For example, the sending of a measurement message may betriggered if the signals are inadequate. Finally, the circuit/module fordetermining whether to send 4928 generates an indication of thedetermination and sends the indication to the memory device 4908, thecircuit/module for sending 4926, or some other component of theapparatus 4900.

The circuit/module for performing a random access procedure 4930 mayinclude circuitry and/or programming (e.g., code for performing a randomaccess procedure 4942 stored on the storage medium 4904) adapted toperform several functions relating to, for example, performing anon-contention-based random access procedure using a dedicated preamblesignature. In some implementations, the circuit/module for performing arandom access procedure 4930 performs the random access operationsdescribed above in conjunction with FIG. 17. In some implementations,the circuit/module for performing a random access procedure 4930performs the random access operations described above in conjunctionwith FIG. 19. In some implementations, the circuit/module for performinga random access procedure 4930 performs the random access operationsdescribed above in conjunction with FIG. 21. In some implementations,the circuit/module for performing a random access procedure 4930performs the random access operations described above in conjunctionwith FIG. 23. In some implementations, the circuit/module for performinga random access procedure 4930 performs the operations described abovein conjunction with FIG. 38.

As mentioned above, programming stored by the storage medium 4904, whenexecuted by the processing circuit 4910, causes the processing circuit4910 to perform one or more of the various functions and/or processoperations described herein. For example, the programming, when executedby the processing circuit 4910, may cause the processing circuit 4910 toperform one or more of the various functions, steps, and/or processesdescribed herein with respect to FIGS. 11, 12, 15-23, 25, 26, 28, 30,32-34, 36, 38, 50, and 51 in various implementations. As shown in FIG.49, the storage medium 4904 may include one or more of the code forreceiving 4932, the code for performing handoffs 4934, the code formeasuring signals 4936, the code for sending 4938, the code fordetermining whether to send 4940, or the code for performing a randomaccess procedure 4942.

Eighth Example Process

FIG. 50 illustrates a process 5000 for communication in accordance withsome aspects of the disclosure. The process 5000 may take place within aprocessing circuit (e.g., the processing circuit 4910 of FIG. 49), whichmay be located in a UT or some other suitable apparatus. In someimplementations, the process 5000 represents operations performed by thecontrol processor 420 of FIG. 4. Of course, in various aspects withinthe scope of the disclosure, the process 5000 may be implemented by anysuitable apparatus capable of supporting communication operations.

At block 5002, an apparatus (e.g., a UT) receives satellite handoffinformation that specifies a handoff time for a particular cell of aparticular satellite. In some aspects, the operations of block 5002 maycorrespond to the operations of block 2504 of FIG. 25.

The satellite handoff information may take various forms as taughtherein. In some aspects, the satellite handoff information may include atable that includes a handoff activation time. In some aspects, thesatellite handoff information may include at least one tune-away time.In some aspects, the handoff information may be defined based, in part,on a satellite pointing error. In some aspects, the handoff informationmay be for at least one future handoff (e.g., the next handoff, a laterhandoff, or some other handoff that will occur in the future). In someaspects, the handoff information may be for the next beam handoff andfor at least one future satellite handoff (e.g., for the next twohandoffs that will occur, the next handoff and some other subsequenthandoff, etc.).

In some implementations, the circuit/module for receiving 4920 of FIG.49 performs the operations of block 5002. In some implementations, thecode for receiving 4932 of FIG. 49 is executed to perform the operationsof block 5002.

At block 5004, the apparatus performs handoff to the particular cell ofthe particular satellite based on the satellite handoff information. Insome aspects, the operations of block 5004 may correspond to theoperations of block 2506 of FIG. 25.

In some aspects, the handoff may involve a change of at least one of: asatellite access network (SAN), a GN antenna, a satellite beam, or aforward service link (FSL) frequency.

In some implementations, the circuit/module for performing a handoff4922 of FIG. 49 performs the operations of block 5004. In someimplementations, the code for performing a handoff 4934 of FIG. 49 isexecuted to perform the operations of block 5004.

In some aspects, the process 5000 may further include measuring signalsfrom at least one satellite, and sending a measurement message based onthe measured signals, wherein the satellite handoff information isreceived as a result of the measurement message being sent. Themeasurement message may include at least one of: measurement data basedon the measured signals, a request to advance handoff timing, or arequest to delay handoff timing. In some aspects, these operations maycorrespond to the operations of blocks 3004 and 3008 of FIG. 30.

In some aspects, the process 5000 may further include receivinginformation indicative of a measurement gap for measuring satellitesignals, wherein the measurement of the signals from the at least onesatellite is conducted during the measurement gap. In some aspects,these operations may correspond to the operations of blocks 3602 and3604 of FIG. 36.

In some aspects, the process 5000 may further include determiningwhether to send the measurement message based on at least one of:whether signals from a current serving satellite are inadequate orwhether signals from a target satellite are inadequate. In some aspects,these operations may correspond to the operations of block 3006 of FIG.30.

In some aspects, the process 5000 may further include sending a messageincluding user terminal capability information, wherein the receivedsatellite handoff information is based on the user terminal capabilityinformation. The user terminal capability information may indicate atleast one of: whether a user terminal can sense multiple beams, whethera user terminal can sense multiple satellites, a user terminalinter-beam tune time, or a user terminal inter-satellite tune time. Thesending of the message including user terminal capability informationmay be triggered as a result of an initial connection to a satellite. Insome aspects, these operations may correspond to the operations of block2606 of FIG. 26.

In some aspects, the process 5000 may further include sending a messageincluding user terminal location information, wherein the receivedsatellite handoff information is based on the user terminal locationinformation. The user terminal location information may include at leastone of: a current user terminal location or a user terminal motionvector. The sending of the message including user terminal locationinformation may be triggered as a result of at least one of: an initialconnection to a satellite, whether a user terminal is beyond ageographical boundary, or whether an error bound has been exceeded. Insome aspects, these operations may correspond to the operations of block2806 of FIG. 28.

In some aspects, the process 5000 may further include receiving adedicated preamble signature, and performing a non-contention-basedrandom access procedure using the dedicated preamble signature. In someaspects, these operations may correspond to the operations of blocks3802 and 3804 of FIG. 38.

In some aspects, the process 5000 may further include determiningwhether to send the measurement message based on at least one of:whether signals from a current serving satellite are inadequate orwhether signals from a target satellite are inadequate. In some aspects,these operations may correspond to the operations of block 2806 of FIG.28.

Ninth Example Process

FIG. 51 illustrates a process 5100 for communication in accordance withsome aspects of the disclosure. The process 5100 may take place within aprocessing circuit (e.g., the processing circuit 4910 of FIG. 49), whichmay be located in a UT or some other suitable apparatus. In someimplementations, the process 5100 represents operations performed by thecontrol processor 420 of FIG. 4. Of course, in various aspects withinthe scope of the disclosure, the process 5100 may be implemented by anysuitable apparatus capable of supporting communication operations.

At block 5102, an apparatus (e.g., a UT) receives satellite and celltransition information that specifies a time to start and a time toterminate communication with a particular cell of a particularsatellite. In some aspects, the operations of block 5102 may correspondto the operations of block 2504 of FIG. 25.

In some implementations, the circuit/module for receiving 4920 of FIG.49 performs the operations of block 5102. In some implementations, thecode for receiving 4932 of FIG. 49 is executed to perform the operationsof block 5102.

At block 5104, the apparatus performs handoff to the particular cell ofthe particular satellite based on the satellite and cell transitioninformation. In some aspects, the operations of block 5104 maycorrespond to the operations of block 2506 of FIG. 25.

In some implementations, the circuit/module for performing a handoff4922 of FIG. 49 performs the operations of block 5104. In someimplementations, the code for performing a handoff 4934 of FIG. 49 isexecuted to perform the operations of block 5104.

In some aspects, the process 5100 further includes: measuring signalsfrom at least one satellite; and sending a measurement message based onthe measured signals, wherein the satellite and cell transitioninformation is received as a result of sending the measurement message.In some aspects, the measurement message includes at least one of:measurement data, a request to advance handoff timing, or a request todelay handoff timing. In some aspects, the process 5100 further includesdetermining whether to send the measurement message based on at leastone of: whether signals from a current serving satellite are inadequate,or whether signals from a target satellite are inadequate. In someaspects, these operations may correspond to the operations of blocks3004-3008 of FIG. 30. In some implementations, the circuit/module formeasuring signals 4924 and/or the circuit/module for determining whetherto send 4928 of FIG. 49 performs these operations. In someimplementations, the code for measuring signals 4936 and/or the code fordetermining whether to send 4940 of FIG. 49 is executed to perform theseoperations.

In some aspects, the process 5100 further includes sending a messageincluding user terminal capability information, wherein the satelliteand cell transition information is based on the user terminal capabilityinformation. In some aspects, the user terminal capability informationindicates at least one of: whether a user terminal can sense multiplecells, whether a user terminal can sense multiple satellites, a userterminal inter-cell tune time, or a user terminal inter-satellite tunetime. In some aspects, the sending of the message including userterminal capability information is triggered as a result of an initialconnection to a satellite. In some aspects, these operations maycorrespond to the operations of blocks 2602-2606 of FIG. 26. In someimplementations, the circuit/module for sending 4926 of FIG. 49 performsthese operations. In some implementations, the code for sending 4938 ofFIG. 49 is executed to perform these operations.

In some aspects, the process 5100 further includes sending a messageincluding user terminal location information, wherein the satellite andcell transition information is based on the user terminal locationinformation. In some aspects, the user terminal location informationincludes a current user terminal location or a user terminal motionvector. In some aspects, the sending of the message including userterminal location information is triggered as a result of at least oneof: an initial connection to a satellite, whether a user terminal isbeyond a geographical boundary, or whether an error bound has beenexceeded. In some aspects, these operations may correspond to theoperations of blocks 2802-2806 of FIG. 28. In some implementations, thecircuit/module for sending 4926 of FIG. 49 performs these operations. Insome implementations, the code for sending 4938 of FIG. 49 is executedto perform these operations.

Additional Aspects

The examples set forth herein are provided to illustrate certainconcepts of the disclosure. Those of ordinary skill in the art willcomprehend that these are merely illustrative in nature, and otherexamples may fall within the scope of the disclosure and the appendedclaims. Based on the teachings herein those skilled in the art shouldappreciate that an aspect disclosed herein may be implementedindependently of any other aspects and that two or more of these aspectsmay be combined in various ways. For example, an apparatus may beimplemented or a method may be practiced using any number of the aspectsset forth herein. In addition, such an apparatus may be implemented orsuch a method may be practiced using other structure, functionality, orstructure and functionality in addition to or other than one or more ofthe aspects set forth herein.

As those skilled in the art will readily appreciate, various aspectsdescribed throughout this disclosure may be extended to any suitabletelecommunication system, network architecture, and communicationstandard. By way of example, various aspects may be applied to wide areanetworks, peer-to-peer network, local area network, other suitablesystems, or any combination thereof, including those described byyet-to-be defined standards.

Many aspects are described in terms of sequences of actions to beperformed by, for example, elements of a computing device. It will berecognized that various actions described herein can be performed byspecific circuits, for example, central processing units (CPUs), graphicprocessing units (GPUs), digital signal processors (DSPs), applicationspecific integrated circuits (ASICs), field programmable gate arrays(FPGAs), or various other types of general purpose or special purposeprocessors or circuits, by program instructions being executed by one ormore processors, or by a combination of both. Additionally, thesesequence of actions described herein can be considered to be embodiedentirely within any form of computer readable storage medium havingstored therein a corresponding set of computer instructions that uponexecution would cause an associated processor to perform thefunctionality described herein. Thus, the various aspects of thedisclosure may be embodied in a number of different forms, all of whichhave been contemplated to be within the scope of the claimed subjectmatter. In addition, for each of the aspects described herein, thecorresponding form of any such aspects may be described herein as, forexample, “logic configured to” perform the described action.

Those of skill in the art will appreciate that information and signalsmay be represented using any of a variety of different technologies andtechniques. For example, data, instructions, commands, information,signals, bits, symbols, and chips that may be referenced throughout theabove description may be represented by voltages, currents,electromagnetic waves, magnetic fields or particles, optical fields orparticles, or any combination thereof.

Further, those of skill in the art will appreciate that the variousillustrative logical blocks, modules, circuits, and algorithm stepsdescribed in connection with the aspects disclosed herein may beimplemented as electronic hardware, computer software, or combinationsof both. To clearly illustrate this interchangeability of hardware andsoftware, various illustrative components, blocks, modules, circuits,and steps have been described above generally in terms of theirfunctionality. Whether such functionality is implemented as hardware orsoftware depends upon the particular application and design constraintsimposed on the overall system. Skilled artisans may implement thedescribed functionality in varying ways for each particular application,but such implementation decisions should not be interpreted as causing adeparture from the scope of the disclosure.

One or more of the components, steps, features and/or functionsillustrated in above may be rearranged and/or combined into a singlecomponent, step, feature or function or embodied in several components,steps, or functions. Additional elements, components, steps, and/orfunctions may also be added without departing from novel featuresdisclosed herein. The apparatus, devices, and/or components illustratedabove may be configured to perform one or more of the methods, features,or steps described herein. The novel algorithms described herein mayalso be efficiently implemented in software and/or embedded in hardware.

It is to be understood that the specific order or hierarchy of steps inthe methods disclosed is an illustration of example processes. Basedupon design preferences, it is understood that the specific order orhierarchy of steps in the methods may be rearranged. The accompanyingmethod claims present elements of the various steps in a sample order,and are not meant to be limited to the specific order or hierarchypresented unless specifically recited therein.

The methods, sequences or algorithms described in connection with theaspects disclosed herein may be embodied directly in hardware, in asoftware module executed by a processor, or in a combination of the two.A software module may reside in RAM memory, flash memory, ROM memory,EPROM memory, EEPROM memory, registers, hard disk, a removable disk, aCD-ROM, or any other form of storage medium known in the art. An exampleof a storage medium is coupled to the processor such that the processorcan read information from, and write information to, the storage medium.In the alternative, the storage medium may be integral to the processor.

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any aspect described herein as “exemplary”is not necessarily to be construed as preferred or advantageous overother aspects. Likewise, the term “aspects” does not require that allaspects include the discussed feature, advantage or mode of operation.

The terminology used herein is for the purpose of describing particularaspects only and is not intended to be limiting of the aspects. As usedherein, the singular forms “a,” “an” and “the” are intended to includethe plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises,”“comprising,” “includes” or “including,” when used herein, specify thepresence of stated features, integers, steps, operations, elements, orcomponents, but do not preclude the presence or addition of one or moreother features, integers, steps, operations, elements, components, orgroups thereof. Moreover, it is understood that the word “or” has thesame meaning as the Boolean operator “OR,” that is, it encompasses thepossibilities of “either” and “both” and is not limited to “exclusiveor” (“XOR”), unless expressly stated otherwise. It is also understoodthat the symbol “/” between two adjacent words has the same meaning as“or” unless expressly stated otherwise. Moreover, phrases such as“connected to,” “coupled to” or “in communication with” are not limitedto direct connections unless expressly stated otherwise.

Any reference to an element herein using a designation such as “first,”“second,” and so forth does not generally limit the quantity or order ofthose elements. Rather, these designations may be used herein as aconvenient method of distinguishing between two or more elements orinstances of an element. Thus, a reference to first and second elementsdoes not mean that only two elements may be used there or that the firstelement must precede the second element in some manner. Also, unlessstated otherwise a set of elements may comprise one or more elements. Inaddition, terminology of the form “at least one of a, b, or c” or “a, b,c, or any combination thereof” used in the description or the claimsmeans “a or b or c or any combination of these elements.” For example,this terminology may include a, or b, or c, or a and b, or a and c, or aand b and c, or 2a, or 2b, or 2c, or 2a and b, and so on.

As used herein, the term “determining” encompasses a wide variety ofactions. For example, “determining” may include calculating, computing,processing, deriving, investigating, looking up (e.g., looking up in atable, a database or another data structure), ascertaining, and thelike. Also, “determining” may include receiving (e.g., receivinginformation), accessing (e.g., accessing data in a memory), and thelike. Also, “determining” may include resolving, selecting, choosing,establishing, and the like.

While the foregoing disclosure shows illustrative aspects, it should benoted that various changes and modifications could be made hereinwithout departing from the scope of the appended claims. The functions,steps or actions of the method claims in accordance with aspectsdescribed herein need not be performed in any particular order unlessexpressly stated otherwise. Furthermore, although elements may bedescribed or claimed in the singular, the plural is contemplated unlesslimitation to the singular is explicitly stated.

What is claimed is:
 1. A method of communication for an apparatus,comprising: identifying a time associated with a particular entry of aset of handoff entries, wherein the set of handoff entries identifies aset of satellites for handoff of the apparatus; determining, based onthe identified time, whether to send a request for an updated set ofhandoff entries; and sending the request for an updated set of handoffentries if the determination is to send the request.
 2. The method ofclaim 1, wherein the set of handoff entries comprises an idle modehandoff table.
 3. The method of claim 1, wherein the time comprises astart time for a handoff to one satellite of the set of satellites. 4.The method of claim 1, wherein the particular entry comprises a lastentry of the set of handoff entries.
 5. The method of claim 1, whereinthe set of satellites is for an idle mode operation of the apparatus. 6.The method of claim 1, wherein: the time indicates when the apparatus isto handoff to one satellite of the set of satellites while the apparatusis in an idle mode.
 7. The method of claim 1, further comprising:sending an indication of the time in conjunction with the sending of therequest.
 8. The method of claim 1, further comprising: sending anindication of a time of validity associated with the set of handoffentries in conjunction with the sending of the request.
 9. The method ofclaim 1, further comprising: receiving the updated set of handoffentries after sending the request; and handing off the apparatus to asatellite identified by the updated set of handoff entries at a timeindicated by the updated set of handoff entries.
 10. The method of claim9, further comprising: receiving an indication of at least one carrierfrequency at which a next cell that provides coverage for the apparatuswill be transmitting, wherein the handoff to the satellite identified bythe updated set of handoff entries is conducted on the at least onecarrier frequency.
 11. The method of claim 1, further comprising:determining location information for the apparatus; and sending thelocation information in conjunction with the sending of the request. 12.An apparatus for communication, comprising: a memory; and a processorcoupled to the memory, the processor and the memory configured to:identify a time associated with a particular entry of a set of handoffentries, wherein the set of handoff entries identifies a set ofsatellites for handoff of the apparatus; determine, based on theidentified time, whether to send a request for an updated set of handoffentries; and send the request for an updated set of handoff entries ifthe determination is to send the request.
 13. A method of communicationfor an apparatus, comprising: identifying a quantity of valid entries ina set of handoff entries, wherein the set of handoff entries identifiesa set of satellites for handoff of the apparatus; determining, based onthe identified quantity, whether to send a request for an updated set ofhandoff entries; and sending the request for an updated set of handoffentries if the determination is to send the request.
 14. The method ofclaim 13, wherein the set of handoff entries comprises an idle modehandoff table.
 15. The method of claim 13, wherein: the set of handoffentries further identifies times at which the apparatus when in idlemode is to handoff to each satellite of the set of satellites.
 16. Themethod of claim 13, wherein the determination of whether to send therequest for an updated set of handoff entries comprises: determiningwhether the set of handoff entries includes only one valid entry. 17.The method of claim 13, further comprising: receiving the updated set ofhandoff entries after sending the request; and handing off the apparatusto a satellite identified by the updated set of handoff entries at atime indicated by the updated set of handoff entries.
 18. The method ofclaim 17, further comprising: receiving an indication of at least onecarrier frequency at which a next cell that provides coverage for theapparatus will be transmitting, wherein the handoff to the satelliteidentified by the updated set of handoff entries is conducted on the atleast one carrier frequency.
 19. The method of claim 13, furthercomprising: determining location information for the apparatus; andsending the location information in conjunction with the sending of therequest.
 20. A method of communication for an apparatus, comprising:identifying a time of validity associated with a set of handoff entries,wherein the set of handoff entries identifies a set of satellites forhandoff of another apparatus; determining, based on the identified timeof validity, whether to send an updated set of handoff entries; andsending the updated set of handoff entries if the determination is tosend the updated set of handoff entries.
 21. The method of claim 20,wherein the set of handoff entries comprises an idle mode handoff table.22. The method of claim 20, wherein the time of validity indicates aduration of time that the set of handoff entries is valid.
 23. Themethod of claim 20, wherein the identification of the time of validitycomprises: receiving an indication of the time of validity.
 24. Themethod of claim 20, wherein the identification of the time of validitycomprises: receiving an indication of a time associated with aparticular entry of the set of handoff entries; and determining the timeof validity based on the received indication.
 25. The method of claim20, wherein the identification of the time of validity comprises:determining a time associated with a last valid entry in the set ofhandoff entries.
 26. The method of claim 20, wherein the set of handoffentries comprises a last set of handoff entries sent by the apparatus tothe other apparatus.
 27. The method of claim 20, further comprising:receiving location information for the other apparatus; and generatingthe updated set of handoff entries based on the location information,wherein the updated set of handoff entries is sent to the otherapparatus.
 28. The method of claim 20, further comprising: receivinglocation information for the other apparatus, wherein the determinationof whether to send the updated set of handoff entries is further basedon the location information.
 29. The method of claim 20, furthercomprising: receiving location information for the other apparatus; anddetermining movement of the other apparatus based on the locationinformation, wherein the determination of whether to send the updatedset of handoff entries is further based on the movement of the otherapparatus.
 30. The method of claim 20, further comprising: receivinglocation information for the other apparatus; determining movement ofthe other apparatus based on the location information; and determininghow many updated handoff entries to send based on the movement of theother apparatus.